2181    Identifying a 35 U.S.C. 112, Sixth Paragraph Limitation [R-9]

This section sets forth guidelines for the examination of 35 U.S.C. 112, sixth paragraph, "means or step plus function" limitations in a claim. These guidelines are based on the Office’s current understanding of the law and are believed to be fully consistent with binding precedent of the Supreme Court, the Federal Circuit and the Federal Circuit’s predecessor courts. These guidelines do not constitute substantive rulemaking and hence do not have the force and effect of law.

The Court of Appeals for the Federal Circuit, in its en banc decision In re Donaldson Co., 16 F.3d 1189, 29 USPQ2d 1845 (Fed. Cir. 1994), decided that a "means-or-step-plus-function" limitation should be interpreted in a manner different than patent examining practice had previously dictated. The Donaldson decision affects only the manner in which the scope of a "means or step plus function" limitation in accordance with 35 U.S.C. 112, sixth paragraph, is interpreted during examination. Donaldson does not directly affect the manner in which any other section of the patent statutes is interpreted or applied.

When making a determination of patentability under 35 U.S.C. 102  or 103, past practice was to interpret a "means or step plus function" limitation by giving it the "broadest reasonable interpretation." Under the PTO’s long-standing practice this meant interpreting such a limitation as reading on any prior art means or step which performed the function specified in the claim without regard for whether the prior art means or step was equivalent to the corresponding structure, material or acts described in the specification. However, in Donaldson, the Federal Circuit stated:

Per our holding, the "broadest reasonable interpretation" that an examiner may give means-plus-function language is that statutorily mandated in paragraph six. Accordingly, the PTO may not disregard the structure disclosed in the specification corresponding to such language when rendering a patentability determination.

I.    DETERMINING WHETHER A CLAIM LIMITATION INVOKES 35 U.S.C. 112, SIXTH PARAGRAPH

The USPTO must apply 35 U.S.C. 112, sixth paragraph in appropriate cases, and give claims their broadest reasonable interpretation, in light of and consistent with the written description of the invention in the application. See Donaldson, 16 F.3d at 1194, 29 USPQ2d at 1850 (stating that 35 U.S.C. 112, sixth paragraph "merely sets a limit on how broadly the PTO may construe means-plus-function language under the rubric of reasonable interpretation.’"). The Federal Circuit has held that applicants (and reexamination patentees) before the USPTO have the opportunity and the obligation to define their inventions precisely during proceedings before the PTO. See In re Morris, 127 F.3d 1048, 1056–57, 44 USPQ2d 1023, 1029–30 (Fed. Cir. 1997) (35 U.S.C. 112, second paragraph places the burden of precise claim drafting on the applicant); In re Zletz, 893 F.2d 319, 322, 13 USPQ2d 1320, 1322 (Fed. Cir. 1989) (manner of claim interpretation that is used by courts in litigation is not the manner of claim interpretation that is applicable during prosecution of a pending application before the PTO); Sage Prods., Inc. v. Devon Indus., Inc., 126 F.3d 1420, 1425, 44 USPQ2d 1103, 1107 (Fed. Cir. 1997) (patentee who had a clear opportunity to negotiate broader claims during prosecution but did not do so, may not seek to expand the claims through the doctrine of equivalents, for it is the patentee, not the public, who must bear the cost of failure to seek protection for this foreseeable alteration of its claimed structure).

If a claim limitation recites a term and associated functional language, the examiner should determine whether the claim limitation invokes 35 U.S.C. 112, sixth paragraph. The claim limitation is presumed to invoke 35 U.S.C. 112, sixth paragraph when it explicitly uses the phrase "means for" or "step for" and includes functional language. That presumption is overcome when the limitation further includes the structure necessary to perform the recited function. TriMed, Inc. v. Stryker Corp., 514 F.3d 1256, 1259-60 (Fed. Cir. 2008) ("Sufficient structure exists when the claim language specifies the exact structure that performs the function in question without need to resort to other portions of the specification or extrinsic evidence for an adequate understanding of the structure."); see also Altiris, Inc. v. Symantec Corp., 318 F.3d 1363, 1376 (Fed. Cir. 2003).

By contrast, a claim limitation that does not use the phrase "means for" or "step for" will trigger the rebuttable presumption that 35 U.S.C. 112, sixth paragraph does not apply. See, e.g., Phillips v. AWH Corp., 415 F.3d 1303, 1311 (Fed. Cir. 2005) (en banc); CCS Fitness, Inc. v. Brunswick Corp., 288 F.3d 1359, 1369 (Fed. Cir. 2002); Personalized Media Commc’ns, LLC v. ITC, 161 F.3d 696, 703-04 (Fed. Cir. 1998). This presumption is a strong one that is not readily overcome. Lighting World, Inc. v. Birchwood Lighting, Inc., 382 F.3d 1354, 1358 (2004); Inventio AG v. Thyssenkrupp Elevator Americas Corp., 649 F.3d 1350, 1356, 99 USPQ2d 1112, 1117 (Fed. Cir. 2011). This strong presumption may be overcome if the claim limitation is shown to use a non-structural term that is "a nonce word or a verbal construct that is not recognized as the name of structure" but is merely a substitute for the term "means for," associated with functional language. Lighting World, 382 F.3d at 1360.

Accordingly, examiners will apply 35 U.S.C. 112, sixth paragraph to a claim limitation if it meets the following 3-prong analysis:

    • (A) the claim limitation uses the phrase "means for" or "step for" or a non-structural term (a term that is simply a substitute for the term "means for");
    • (B) the phrase "means for" or "step for" or the non-structural term must be modified by functional language; and
    • (C) the phrase "means for" or "step for" or the non-structural term must not be modified by sufficient structure, material, or acts for achieving the specified function.

A.   The Claim Limitation Uses the Phrase "Means For" Or "Step For" Or A Non-Structural Term (A Term That Is Simply A Substitute for the Term "Means For")

With respect to the first prong of this analysis, a claim element that does not include the phrase "means for" or "step for" will not be presumed to invoke 35 U.S.C. 112, sixth paragraph. When the claim limitation does not use the phrase "means for," examiners should determine whether the presumption that 35 U.S.C. 112, paragraph 6 does not apply is overcome if the claim limitation uses a non-structural term (a term that is simply a substitute for the term "means for"). The following is a list of non-structural terms that may invoke 35 U.S.C. 112, paragraph 6: "mechanism for," "module for," "device for," "unit for," "component for," "element for," "member for," "apparatus for," "machine for," or "system for." Welker Bearing Co., v. PHD, Inc., 550 F.3d 1090, 1096 (Fed. Cir. 2008); Massachusetts Inst. of Tech. v. Abacus Software, 462 F.3d 1344, 1354 (Fed. Cir. 2006); Personalized Media, 161 F.3d at 704; Mas-Hamilton Group v. LaGard, Inc., 156 F.3d 1206, 1214-1215 (Fed. Cir. 1998). This list is not exhaustive, and other non-structural terms may invoke 35 U.S.C. 112, paragraph 6.

However, 35 U.S.C. 112, paragraph 6 will not apply if persons of ordinary skill in the art reading the specification understand the term to be the name for the structure that performs the function, even when the term covers a broad class of structures or identifies the structures by their function (e.g., "filters," "brakes," "clamp," "screwdriver," and "locks"). Lighting World, 382 F.3d at 1360; Apex Inc. v. Raritan Computer, Inc., 325 F.3d 1364, 1372-73 (Fed. Cir. 2003); CCS Fitness, 288 F.3d at 1369; Watts v. XL Sys. Inc., 232 F.3d 877, 880-81 (Fed. Cir. 2000); Personalized Media, 161 F.3d at 704; Greenberg v. Ethicon Endo-Surgery, Inc., 91 F.3d 1580, 1583 (Fed. Cir. 1996) ("Many devices take their names from the functions they perform.") The term is not required to denote a specific structure or a precise physical structure to avoid the application of 35 U.S.C. 112, paragraph 6. See Watts, 232 F.3d at 880; Inventio AG v. Thyssenkrupp Elevator Americas Corp., 649 F.3d 1350 (Fed. Cir. 2011)(The court concluded the claim terms "modernizing device" and "computing unit" when read in light of the specification connoted sufficient, definite structure to one of skill in the art to preclude application of 35 U.S.C. 112, sixth paragraph). The following are examples of structural terms that have been found not to invoke 35 U.S.C. 112, paragraph 6: "circuit," "detent mechanism," "digital detector," "reciprocating member," "connector assembly," "perforation," "sealingly connected joints," and "eyeglass hanger member." Linear Tech. Corp. v. Impala Linear Corp., 379 F.3d 1311, 1321 (Fed. Cir. 2004); Apex, 325 F.3d at 1373; Greenberg, 91 F.3d at 1583-84; Personalized Media, 161 F.3d at 704-05; CCS Fitness, 288 F.3d at 1369-70; Lighting World, 382 F.3d at 1358-63; Cole v. Kimberly-Clark Corp., 102 F.3d 524, 531 (Fed. Cir. 1996); Watts, 232 F.3d at 881; Al-Site Corp. v. VSI Int’l, Inc., 174 F.3d 1308, 1318-19 (Fed. Cir. 1999).

If the examiner has not interpreted a claim limitation as invoking 35 U.S.C. 112, sixth paragraph and an applicant wishes to have the claim limitation treated under 35 U.S.C. 112, sixth paragraph, applicant must either: (A) amend the claim to include the phrase "means for" or "step for" ; or (B) rebut the presumption that 35 U.S.C. 112, sixth paragraph does not apply by showing that the claim limitation is written as a function to be performed and does not recite sufficient structure, material, or acts. See Watts v. XL Systems, Inc., 232 F.3d 877, 56 USPQ2d 1836 (Fed. Cir. 2000) (Claim limitations were held not to invoke 35 U.S.C. 112, sixth paragraph, because the absence of the term "means" raised the presumption that the limitations were not in means-plus-function form and the applicant did not rebut that presumption.); see also Masco Corp. v. United States, 303 F.3d 1316, 1327, 64 USPQ2d 1182, 1189 (Fed. Cir. 2002) ("[W]here a method claim does not contain the term ‘step[s] for,’ a limitation of that claim cannot be construed as a step-plus-function limitation without a showing that the limitation contains no act.").

Some of the following examples illustrate situations where the phrase "means for" or "step for" was not used but either the Board or courts nevertheless determined that the claim limitation fell within the scope of 35 U.S.C. 112, sixth paragraph. Note that the examples are fact specific and should not be applied as per se rules. See Signtech USA, Ltd. v. Vutek, Inc., 174 F.3d 1352, 1356, 50 USPQ2d 1372, 1374– 75 (Fed. Cir.1999) ("ink delivery means positioned on …" invokes 35 U.S.C. 112, sixth paragraph since the phrase "ink delivery means" is equivalent to "means for ink delivery"); ; Seal-Flex, Inc. v. Athletic Track and Court Construction, 172 F.3d 836, 850, 50 USPQ2d 1225, 1234 (Fed. Cir. 1999) (Radar, J., concurring) ("claim elements without express step-plus-function language may nevertheless fall within 112  6 if they merely claim the underlying function without recitation of acts for performing that function…In general terms, the underlying function’ of a method claim element corresponds to what that element ultimately accomplishes in relationship to what the other elements of the claim and the claim as a whole accomplish. Acts,’ on the other hand, correspond to how the function is accomplished…If the claim element uses the phrase step for,’ then § 112, 6 is presumed to apply…On the other hand, the term step’ alone and the phrase steps of’ tend to show that § 112, 6 does not govern that limitation."); Personalized Media Communications LLC v. ITC, 161 F.3d 696, 703–04, 48 USPQ2d 1880, 1886–87 (Fed. Cir. 1998); Mas-Hamilton Group v. LaGard Inc., 156 F.3d 1206, 1213, 48 USPQ2d 1010, 1016 (Fed. Cir. 1998) ("lever moving element for moving the lever" and "movable link member for holding the lever…and for releasing the lever" were construed as means-plus-function limitations invoking 35 U.S.C. 112, sixth paragraph since the claimed limitations were described in terms of their function not their mechanical structure); Ethicon, Inc. v. United States Surgical Corp., 135 F.3d 1456, 1463, 45 USPQ2d 1545, 1550 (Fed. Cir. 1998) ("use of the word means ‘gives rise to a presumption that the inventor used the term advisedly to invoke the statutory mandates for means-plus-function clauses’"). However, compareAl-Site Corp. v. VSI Int’l, Inc., 174 F.3d 1308, 1317-19, 50 USPQ2d 1161, 1166-67 (Fed. Cir. 1999) (although the claim elements "eyeglass hanger member" and "eyeglass contacting member" include a function, these claim elements do not invoke 35 U.S.C. 112, sixth paragraph because the claims themselves contain sufficient structural limitations for performing these functions); O.I. Corp. v. Tekmar, 115 F.3d 1576, 1583, 42 USPQ2d 1777, 1782 (Fed. Cir. 1997) (method claim that paralleled means-plus-function apparatus claim but lacked "step for" language did not invoke 35 U.S.C. 112, sixth paragraph). Thus, absent a determination that a claim limitation invokes 35 U.S.C. 112, sixth paragraph, the broadest reasonable interpretation will not be limited to "corresponding structure…and equivalents thereof." Morris, 127 F.3d at 1055, 44 USPQ2d at 1028 ("no comparable mandate in the patent statute that relates the claim scope of non-§ 112  paragraph 6 claims to particular matter found in the specification").

When applicant uses the phrase "means for" or "step for" in the preamble, a rejection under 35 U.S.C. 112, second paragraph may be appropriate when it is unclear whether the preamble is reciting a means (or step) plus function limitation or whether the preamble is merely stating the intended use of the claimed invention. If applicant uses a structural or non-structural term with the word "for" in the preamble, the examiner should not construe such phrase as reciting a means-plus-function limitation.

B.   The Phrase "Means For" Or "Step For" Or the Non-Structural Term Must Be Modified By Functional Language

With respect to the second prong of this analysis, it must be clear that the element in the claims is set forth, at least in part, by the function it performs as opposed to the specific structure, material, or acts that perform the function. See York Prod., Inc. v. Central Tractor Farm & Family Center, 99 F.3d 1568, 1574, 40 USPQ2d 1619, 1624 (Fed. Cir. 1996) (holding that a claim limitation containing the term "means" does not invoke 35 U.S.C. 112, sixth paragraph, if the claim limitation does not link the term "means" to a specific function). Caterpillar Inc. v. Detroit Diesel Corp., 41 USPQ2d 1876, 1882 (N.D. Ind. 1996) (35 U.S.C. 112, sixth paragraph, "applies to functional method claims where the element at issue sets forth a step for reaching a particular result, but not the specific technique or procedure used to achieve the result."); O.I. Corp., 115 F.3d at 1582-83, 42 USPQ2d at 1782 (With respect to process claims, "[35 U.S.C. 112, sixth paragraph] is implicated only when steps plus function without acts are present…If we were to construe every process claim containing steps described by an ‘ing’ verb, such as passing, heating, reacting, transferring, etc., into a step-plus-function, we would be limiting process claims in a manner never intended by Congress." (Emphasis in original).). See also Baran v. Medical Device Techs., Inc., 616 F.3d 1309, 1317 (Fed. Cir. 2010) (the claimed function may include the functional language that precedes the phrase "means for.") However, "the fact that a particular mechanism…is defined in functional terms is not sufficient to convert a claim element containing that term into a ‘means for performing a specified function’ within the meaning of section 112 (6)." Greenberg v. Ethicon Endo-Surgery, Inc., 91 F.3d 1580, 1583, 39 USPQ2d 1783, 1786 (Fed. Cir. 1996) ("detent mechanism" defined in functional terms was not intended to invoke 35 U.S.C. 112, sixth paragraph). See also Al-Site Corp. v. VSI International Inc., 174 F.3d 1308, 1318, 50 USPQ2d 1161, 1166–67 (Fed. Cir. 1999) (although the claim elements "eyeglass hanger member" and "eyeglass contacting member" include a function, these claim elements do not invoke 35 U.S.C. 112, sixth paragraph, because the claims themselves contain sufficient structural limitations for performing those functions). Also, a statement of function appearing only in the claim preamble is generally insufficient to invoke 35 U.S.C. 112, sixth paragraph. O.I. Corp., 115 F.3d at 1583, 42 USPQ2d at 1782 ("[A] statement in a preamble of a result that necessarily follows from performing a series of steps does not convert each of those steps into step- plus-function clauses. The steps of ‘passing’ are not individually associated in the claims with functions performed by the steps of passing.").

C.   The Phrase "Means For" Or "Step For" Or the Non-Structural Term Must Not Be Modified By Sufficient Structure, Material, or Acts for Achieving the Specified Function

With respect to the third prong of this analysis, the phrase "means for" or "step for" or the non-structural term recited in the claim must not be modified by sufficient structure, material, or acts for achieving the specified function. See Seal-Flex, 172 F.3d at 849, 50 USPQ2d at 1234 (Radar, J., concurring) ("Even when a claim element uses language that generally falls under the step-plus-function format, however, 112  ¶ 6 still does not apply when the claim limitation itself recites sufficient acts for performing the specified function."); Envirco Corp. v. Clestra Cleanroom, Inc., 209 F.3d 1360, 54 USPQ2d 1449 (Fed. Cir. 2000) (holding "second baffle means" does not invoke 35 U.S.C. 112, sixth paragraph, because the word "baffle" itself imparts structure and the claim further recites the structure of the baffle); Rodime PLC v. Seagate Technology, Inc., 174 F.3d 1294, 1303–04, 50 USPQ2d 1429, 1435–36 (Fed. Cir. 1999) (holding "positioning means for moving" does not invoke 35 U.S.C. 112, sixth paragraph, because the claim further provides a list of the structure underlying the means and the detailed recitation of the structure for performing the moving function removes this element from the purview of 35 U.S.C. 112, sixth paragraph); Cole v. Kimberly-Clark Corp., 102 F.3d 524, 531, 41 USPQ2d 1001, 1006 (Fed. Cir. 1996) (holding "perforation means…for tearing" does not invoke 35 U.S.C. 112, sixth paragraph, because the claim describes the structure supporting the tearing function (i.e., perforation)). In other cases, the Federal Circuit has held otherwise. See Unidynamics Corp. v. Automatic Prod. Int’l, 157 F.3d 1311, 1319, 48 USPQ2d 1099, 1104 (Fed. Cir. 1998) (holding "spring means" does invoke 35 U.S.C. 112, sixth paragraph).

Examiners will apply 35 U.S.C. 112, sixth paragraph to a claim limitation that uses a non-structural term associated with functional language, unless the non-structural term is (1) preceded by a structural modifier, defined in the specification as a particular structure or known by one skilled in the art, that denotes the type of structural device (e.g., "filters"), or (2) modified by sufficient structure or material for achieving the claimed function.

A limitation will not invoke 35 U.S.C. 112, sixth paragraph if there is a structural modifier that further describes the non-structural term. For example, although a non-structural term like "mechanism" standing alone may invoke 35 U.S.C. 112, sixth paragraph when coupled with a function, it will not invoke 35 U.S.C. 112, sixth paragraph when it is preceded by a structural modifier (e.g., "detent mechanism"). Greenberg, 91 F.3d at 1583 (holding that the term "detent mechanism" did not to invoke 35 U.S.C. 112, sixth paragraph because the structural modifier "detent" denotes a type of structural device with a generally understood meaning in the mechanical arts). By contrast, a non-structural term (e.g., "mechanism," "element," "member") coupled with a function may invoke 35 U.S.C. 112, sixth paragraph when it is preceded by a non-structural modifier that does not have any generally understood structural meaning in the art (e.g., "colorant selection mechanism," "lever moving element," or "movable link member"). Massachusetts Inst. of Tech., 462 F.3d at 1354; Mas-Hamilton, 156 F.3d at 1214-1215.

To determine whether a word, term, or phrase coupled with a function denotes structure, examiners should check whether: (1) the specification provides a description sufficient to inform one of ordinary skill in the art that the term denotes structure; (2) general and subject matter specific dictionaries provide evidence that the term has achieved recognition as a noun denoting structure; and (3) the prior art provides evidence that the term has an art-recognized structure to perform the claimed function. Ex parte Rodriguez, 92 USPQ2d 1395, 1404 (Bd. Pat. App. & Int. 2009) (precedential).

During examination, however, applicants have the opportunity and the obligation to define their inventions precisely, including whether a claim limitation invokes 35 U.S.C. 112, sixth paragraph. Thus, if the phrase "means for" or "step for" or non-structural term is modified by sufficient structure, material or acts for achieving the specified function, the USPTO will not apply 35 U.S.C. 112, sixth paragraph, until such modifying language is deleted from the claim limitation.

It is necessary to decide on an element by element basis whether 35 U.S.C. 112, sixth paragraph, applies. Not all terms in a means-plus-function or step-plus-function clause are limited to what is disclosed in the written description and equivalents thereof, since 35 U.S.C. 112, sixth paragraph, applies only to the interpretation of the means or step that performs the recited function. See, e.g., IMS Technology Inc. v. Haas Automation Inc., 206 F.3d 1422, 54 USPQ2d 1129 (Fed. Cir. 2000) (the term "data block" in the phrase "means to sequentially display data block inquiries" was not the means that caused the sequential display, and its meaning was not limited to the disclosed embodiment and equivalents thereof.). Each claim must be independently reviewed to determine the applicability of 35 U.S.C. 112, sixth paragraph, even where the application contains substantially similar process and apparatus claims. O.I. Corp., 115 F.3d at 1583-1584, 42 USPQ2d at 1782 ("We understand that the steps in the method claims are essentially in the same language as the limitations in the apparatus claim, albeit without the ‘means for’ qualification…Each claim must be independently reviewed in order to determine if it is subject to the requirements of section 112, ¶ 6. Interpretation of claims would be confusing indeed if claims that are not means- or step- plus function were to be interpreted as if they were, only because they use language similar to that used in other claims that are subject to this provision.").

Where a claim limitation meets the 3-prong analysis and is being treated under 35 U.S.C. 112, sixth paragraph, the examiner will include a statement in the Office action that the claim limitation is being treated under 35 U.S.C. 112, sixth paragraph. See MPEP § 2181, subsection VI, below. If a claim limitation uses the phrase "means for" or "step for," but the examiner determines that either the second prong or the third prong of the 3-prong analysis is not met, then in these situations, the examiner must include a statement in the Office action explaining the reasons why a claim limitation which uses the phrase "means for" or "step for" is not being treated under 35 U.S.C. 112, sixth paragraph.

In the event that it is unclear whether the claim limitation falls within the scope of 35 U.S.C. 112, sixth paragraph, a rejection under 35 U.S.C. 112, second paragraph may be appropriate.

II.   DESCRIPTION NECESSARY TO SUPPORT A CLAIM LIMITATION WHICH INVOKES 35 U.S.C. 112, SIXTH PARAGRAPH

35 U.S.C. 112, sixth paragraph states that a claim limitation expressed in means-plus-function language "shall be construed to cover the corresponding structure…described in the specification and equivalents thereof." "If one employs means plus function language in a claim, one must set forth in the specification an adequate disclosure showing what is meant by that language. If an applicant fails to set forth an adequate disclosure, the applicant has in effect failed to particularly point out and distinctly claim the invention as required by the second paragraph of section 112." In re Donaldson Co., 16 F.3d 1189, 1195, 29 USPQ2d 1845, 1850 (Fed. Cir. 1994) (in banc).

A.   The Corresponding Structure Must Be Disclosed In the Specification Itself in A Way That One Skilled In the Art Will Understand What Structure Will Perform the Recited Function

The proper test for meeting the definiteness requirement is that the corresponding structure (or material or acts) of a means (or step)-plus-function limitation must be disclosed in the specification itself in a way that one skilled in the art will understand what structure (or material or acts) will perform the recited function. See Atmel Corp. v. Information Storage Devices, Inc., 198 F.3d 1374, 1381, 53 USPQ2d 1225, 1230 (Fed. Cir. 1999). In Atmel, the patentee claimed an apparatus that included a "high voltage generating means" limitation, thereby invoking 35 U.S.C. 112, sixth paragraph. The specification incorporated by reference a non-patent document from a technical journal, which described a particular high voltage generating circuit. The Federal Circuit concluded that the title of the article in the specification may, by itself, be sufficient to indicate to one skilled in the art the precise structure of the means for performing the recited function, and it remanded the case to the district court "to consider the knowledge of one skilled in the art that indicated, based on unrefuted testimony, that the specification disclosed sufficient structure corresponding to the high-voltage means limitation." Id. at 1382, 53 USPQ2d at 1231.

The disclosure of the structure (or material or acts) may be implicit or inherent in the specification if it would have been clear to those skilled in the art what structure (or material or acts) corresponds to the means (or step)-plus-function claim limitation. See Id. at 1380, 53 USPQ2d at 1229; In re Dossel, 115 F.3d 942, 946-47, 42 USPQ2d 1881, 1885 (Fed. Cir. 1997). If there is no disclosure of structure, material or acts for performing the recited function, the claim fails to satisfy the requirements of 35 U.S.C. 112, second paragraph. "[A] bare statement that known techniques or methods can be used does not disclose structure" in the context of a means plus function limitation. Biomedino, LLC v. Waters Technology Corp ., 490 F.3d 946, 952, 83 USPQ2d 1118, 1123 (Fed. Cir. 2007)(Disclosure that an invention "may be controlled by known differential pressure, valving and control equipment" was not a disclosure of any structure corresponding to the claimed "control means for operating [a] valving " and the claim was held indefinite.). See alsoBudde v. Harley-Davidson, Inc., 250 F.3d 1369, 1376, 58 USPQ2d 1801, 1806 (Fed. Cir. 2001); Cardiac Pacemakers, Inc. v. St. Jude Med., Inc., 296 F.3d 1106, 1115-18, 63 USPQ2d 1725, 1731-34 (Fed. Cir. 2002) (Court interpreted the language of the "third monitoring means for monitoring the ECG signal…for activating …" to require the same means to perform both functions and the only entity referenced in the specification that could possibly perform both functions is the physician. The court held that excluding the physician, no structure accomplishes the claimed dual functions. Because no structure disclosed in the embodiments of the invention actually performs the claimed dual functions, the specification lacks corresponding structure as required by 35 U.S.C. 112, sixth paragraph, and fails to comply with 35 U.S.C. 112, second paragraph.).

Whether a claim reciting an element in means- (or step-) plus-function language fails to comply with 35 U.S.C. 112, second paragraph, because the specification does not disclose adequate structure (or material or acts) for performing the recited function is closely related to the question of whether the specification meets the description requirement in 35 U.S.C. 112, first paragraph. See In re Noll, 545 F.2d 141, 149, 191 USPQ 721, 727 (CCPA 1976) (unless the means-plus-function language is itself unclear, a claim limitation written in means-plus- function language meets the definiteness requirement in 35 U.S.C. 112, second paragraph, so long as the specification meets the written description requirement in 35 U.S.C. 112, first paragraph). In Aristocrat Techs. Australia Pty Ltd. v. Int’l Game Tech., 521 F.3d 1328, 1336-37 (Fed. Cir. 2008), the court stated:

Enablement of a device requires only the disclosure of sufficient information so that a person of ordinary skill in the art could make and use the device. A section 112 paragraph 6 disclosure, however, serves the very different purpose of limiting the scope of the claim to the particular structure disclosed, together with equivalents. … For example, in Atmel Corp. v. Information Storage Devices, Inc., 198 F.3d 1374, 1380 (Fed. Cir. 1999), the court embraced the proposition that ‘consideration of the understanding of one skilled in the art in no way relieves the patentee of adequately disclosing sufficient structure in the specification.’ It is not enough for the patentee simply to state or later argue that persons of ordinary skill in the art would know what structures to use to accomplish the claimed function. The court in Biomedino, LLC v. Waters Technologies Corp., 490 F.3d 946, 953 (Fed. Cir. 2007), put the point this way: ‘The inquiry is whether one of skill in the art would understand the specification itself to disclose a structure, not simply whether that person would be capable of implementing that structure.’

The invocation of 35 U.S.C. 112, sixth paragraph, does not exempt an applicant from compliance with 35 U.S.C. 112, first and second paragraphs. See Donaldson, 16 F.3d at 1195, 29 USPQ2d at 1850; In re Knowlton, 481 F.2d 1357, 1366, 178 USPQ 486, 493 (CCPA 1973) ("[The sixth paragraph of section 112] cannot be read as creating an exception either to the description requirement of the first paragraph … or to the definiteness requirement found in the second paragraph of section 112. Means-plus-function language can be used in the claims, but the claims must still accurately define the invention.").

Under certain limited circumstances, the written description does not have to explicitly describe the structure (or material or acts) corresponding to a means- (or step-) plus-function limitation to particularly point out and distinctly claim the invention as required by 35 U.S.C. 112, second paragraph. See Dossel, 115 F.3d at 946, 42 USPQ2d at 1885. Under proper circumstances, drawings may provide a written description of an invention as required by 35 U.S.C. 112. Vas-Cath, Inc. v. Mahurkar, 935 F.2d 1555, 1565, 19 USPQ2d 1111, 1118 (Fed. Cir. 1991). Further, disclosure of structure corresponding to a means-plus-function limitation may be implicit in the written description if it would have been clear to those skilled in the art what structure must perform the function recited in the means-plus-function limitation. See Atmel Corp. v. Information Storage Devices Inc., 198 F.3d 1374, 1379, 53 USPQ2d 1225, 1228 (Fed. Cir. 1999) (stating that the "one skilled in the art" analysis should apply in determining whether sufficient structure has been disclosed to support a means-plus-function limitation and that the USPTO’s recently issued proposed Supplemental Guidelines are consistent with the court’s holding on this point); Dossel, 115 F.3d at 946–47, 42 USPQ2d at 1885 ("Clearly, a unit which receives digital data, performs complex mathematical computations and outputs the results to a display must be implemented by or on a general or special purpose computer (although it is not clear why the written description does not simply state ‘computer’ or some equivalent phrase.)").

B.   Computer-Implemented Means-Plus-Function Limitations

For a computer-implemented means-plus-function claim limitation invoking 35 U.S.C. 112, sixth paragraph, a general purpose computer is usually sufficient for the corresponding structure for performing a general computing function (e.g., "means for storing data"), but the corresponding structure for performing a specific function is required to be more than simply a general purpose computer or microprocessor. In In re Katz Interactive Call Processing Patent Litigation, 639 F.3d 1303, 1316 (Fed. Cir. 2011), the court stated:

Those cases involved specific functions that would need to be implemented by programming a general purpose computer to convert it into a special purpose computer capable of performing those specified functions. … By contrast, in the seven claims identified above, Katz has not claimed a specific function performed by a special purpose computer, but has simply recited the claimed functions of ‘processing,’ ‘receiving,’ and ‘storing.’ Absent a possible narrower construction of the terms ‘processing,’ ‘receiving,’ and ‘storing,’ discussed below, those functions can be achieved by any general purpose computer without special programming. As such, it was not necessary to disclose more structure than the general purpose processor that performs those functions. Those seven claims do not run afoul of the rule against purely functional claiming, because the functions of ‘processing,’ ‘receiving,’ and ‘storing’ are coextensive with the structure disclosed, i.e., a general purpose processor.).

To claim a means for performing a specific computer-implemented function and then to disclose only a general purpose computer as the structure designed to perform that function amounts to pure functional claiming. Aristocrat, 521 F.3d 1328 at 1333. In this instance, the structure corresponding to a 35 U.S.C. 112, sixth paragraph claim limitation for a computer-implemented function must include the algorithm needed to transform the general purpose computer or microprocessor disclosed in the specification. Aristocrat, 521 F.3d at 1333; Finisar Corp. v. DirecTV Group, Inc., 523 F.3d 1323, 1340 (Fed. Cir. 2008); WMS Gaming, Inc. v. Int’l Game Tech., 184 F.3d 1339, 1349 (Fed. Cir. 1999). The corresponding structure is not simply a general purpose computer by itself but the special purpose computer as programmed to perform the disclosed algorithm. Aristocrat, 521 F.3d at 1333. Thus, the specification must sufficiently disclose an algorithm to transform a general purpose microprocessor to the special purpose computer. Aristocrat, 521 F.3d at 1338 ("Aristocrat was not required to produce a listing of source code or a highly detailed description of the algorithm to be used to achieve the claimed functions in order to satisfy 35 U.S.C. 112  P 6. It was required, however, to at least disclose the algorithm that transforms the general purpose microprocessor to a ‘special purpose computer programmed to perform the disclosed algorithm.’ WMS Gaming, 184 F.3d at 1349.") An algorithm is defined, for example, as "a finite sequence of steps for solving a logical or mathematical problem or performing a task." Microsoft Computer Dictionary, Microsoft Press, 5th edition, 2002. Applicant may express the algorithm in any understandable terms including as a mathematical formula, in prose, in a flow chart, or "in any other manner that provides sufficient structure." Finisar, 523 F.3d at 1340; see also Intel Corp. v. VIA Techs., Inc., 319 F.3d 1357, 1366 (Fed. Cir. 2003); In re Dossel, 115 F.3d 942, 946-47 (Fed. Cir.1997); Typhoon Touch Inc. v. Dell Inc., 659 F.3d 1376, 1385 (Fed. Cir. 2011); In re Aoyama, 656 F.3d 1293, 1306 (Fed. Cir. 2011).

A rejection under 35 U.S.C. 112, second paragraph is appropriate if the specification discloses no corresponding algorithm associated with a computer or microprocessor. Aristocrat, 521 F.3d at 1337-38. For example, mere reference to a general purpose computer with appropriate programming without providing an explanation of the appropriate programming, or simply reciting "software" without providing detail about the means to accomplish the software function, would not be an adequate disclosure of the corresponding structure to satisfy the requirements of 35 U.S.C. 112, second paragraph. Aristocrat, 521 F.3d at 1334; Finisar, 523 F.3d at 1340-41. In addition, merely referencing a specialized computer (e.g., a "bank computer"), some undefined component of a computer system (e.g., "access control manager"), "logic," "code," or elements that are essentially a black box designed to perform the recited function, will not be sufficient because there must be some explanation of how the computer or the computer component performs the claimed function. Blackboard, Inc. v. Desire2Learn, Inc., 574 F.3d 1371, 1383-1385 (Fed. Cir. 2009); Net MoneyIN, Inc. v. VeriSign, Inc., 545 F.3d 1359, 1366-67 (Fed. Cir. 2008); Rodriguez, 92 USPQ2d at 1405-06.

In several Federal Circuit cases, the patentees argued that the requirement for the disclosure of an algorithm can be avoided if one of ordinary skill in the art is capable of writing the software to convert a general purpose computer to a special purpose computer to perform the claimed function. See, e.g., Blackboard, 574 F.3d at 1385; Biomedino, 490 F.3d at 952; Atmel Corp., 198 F.3d at 1380. Such argument was found to be unpersuasive because the understanding of one skilled in the art does not relieve the patentee of the duty to disclose sufficient structure to support means-plus-function claim terms. Blackboard, 574 F.3d at 1385 ("A patentee cannot avoid providing specificity as to structure simply because someone of ordinary skill in the art would be able to devise a means to perform the claimed function."); Atmel Corp., 198 F.3d at 1380 ("[C]onsideration of the understanding of one skilled in the art in no way relieves the patentee of adequately disclosing sufficient structure in the specification."). The specification must explicitly disclose the algorithm for performing the claimed function, and simply reciting the claimed function in the specification will not be a sufficient disclosure for an algorithm which, by definition, must contain a sequence of steps. Blackboard, 574 F.3d at 1384 (stating that language that simply describes the function to be performed describes an outcome, not a means for achieving that outcome); Microsoft Computer Dictionary, Microsoft Press, 5th edition, 2002; see also Encyclopaedia Britannica, Inc. v. Alpine Elecs., Inc., 355 Fed. Appx. 389, 394-95, 2009 U.S. App. Lexis. 26358, 10-16 (Fed. Cir. 2009) (holding that implicit or inherent disclosure of a class of algorithms for performing the claimed functions is not sufficient, and the purported "one-step" algorithm is not an algorithm at all) (unpublished).

If the specification explicitly discloses an algorithm, the sufficiency of the disclosure of the algorithm must be determined in light of the level of ordinary skill in the art. Aristocrat, 521 F.3d at 1337; AllVoice Computing PLC v. Nuance Commc’ns, Inc., 504 F.3d 1236, 1245 (Fed. Cir. 2007); Intel Corp., 319 F.3d at 1366-67 (knowledge of a person of ordinary skill in the art can be used to make clear how to implement a disclosed algorithm). The examiner should determine whether one skilled in the art would know how to program the computer to perform the necessary steps described in the specification (i.e., the invention is enabled), and that the inventor was in possession of the invention (i.e., the invention meets the written description requirement). Thus, the specification must sufficiently disclose an algorithm to transform a general purpose microprocessor to a special purpose computer so that a person of ordinary skill in the art can implement the disclosed algorithm to achieve the claimed function. Aristocrat, 521 F.3d at 1338.

Often the supporting disclosure for a computer-implemented invention discusses the implementation of the functionality of the invention through hardware, software, or a combination of both. In this situation, a question can arise as to which mode of implementation supports the means-plus-function limitation. The language of 35 U.S.C. 112, sixth paragraph requires that the recited "means" for performing the specified function shall be construed to cover the corresponding "structure or material" described in the specification and equivalents thereof. Therefore, by choosing to use a means-plus-function limitation and invoke 35 U.S.C. 112, sixth paragraph, applicant limits that claim limitation to the disclosed structure, i.e., implementation by hardware or the combination of hardware and software, and equivalents thereof. Therefore, the examiner should not construe the limitation as covering pure software implementation.

However, if there is no corresponding structure disclosed in the specification (i.e., the limitation is only supported by software and does not correspond to an algorithm and the computer or microprocessor programmed with the algorithm), the limitation should be deemed indefinite as discussed above, and the claim should be rejected under 35 U.S.C. 112, second paragraph. It is important to remember that claims must be interpreted as a whole; so, a claim that includes a means-plus-function limitation that corresponds to software per se (and is thus indefinite for lacking structural support in the specification) is not necessarily directed as a whole to software per se unless the claim lacks other structural limitations.

C.   The Supporting Disclosure Clearly Links or Associate the Disclosed Structure, Material, or Acts to the Claimed Function

The structure disclosed in the written description of the specification is the corresponding structure only if the written description of the specification or the prosecution history clearly links or associates that structure to the function recited in a means-plus-function claim limitation under 35 U.S.C. 112, sixth paragraph. See B. Braun Medical Inc., v. Abbott Laboratories, 124 F.3d 1419, 1424, 43 USPQ2d 1896, 1900 (Fed. Cir. 1997). The requirement that a particular structure be clearly linked with the claimed function in order to qualify as corresponding structure is the quid pro quo for the convenience of employing 35 U.S.C. 112, sixth paragraph, and is also supported by the requirement of 35 U.S.C. 112, second paragraph, that an invention must be particularly pointed out and distinctly claimed. See Medical Instrumentation & Diagnostics Corp. v. Elekta AB, 344 F.3d 1205, 1211, 68 USPQ2d 1263, 1268. For a means (or step) plus function claim limitation that invokes 35 U.S.C. 112, sixth paragraph, a rejection under 35 U.S.C. 112, second paragraph, is appropriate if one of ordinary skill in the art cannot identify what structure, material, or acts disclosed in the written description of the specification perform the claimed function.

III.   DETERMINING 35 U.S.C. 112  SECOND PARAGRAPH COMPLIANCE WHEN 35 U.S.C. 112  SIXTH PARAGRAPH IS INVOKED

Once the examiner determines that a claim limitation is a means-plus-function limitation invoking 35 U.S.C. 112, sixth paragraph, the examiner should determine the claimed function and then review the written description of the specification to determine whether the corresponding structure, material, or acts that perform the claimed function are disclosed. Note that drawings may provide a written description of an invention as required by 35 U.S.C. 112. See Vas-Cath Inc. v. Mahurkar, 935 F.2d 1555, 1565 (Fed. Cir. 1991). The corresponding structure, material, or acts may be disclosed in the original drawings, figures, tables, or sequence listing. However, the corresponding structure, material, or acts cannot include any structure, material, or acts disclosed only in the material incorporated by reference or a prior art reference. See Pressure Prods. Med. Supplies, Inc. v. Greatbatch Ltd., 599 F.3d 1308, 1317 (Fed. Cir. 2010) (stating, "Simply mentioning prior art references in a patent does not suffice as a specification description to give the patentee outright claim to all of the structures disclosed in those references."); Atmel Corp. v. Info. Storage Devices, Inc., 198 F.3d 1374, 1381 (Fed. Cir. 1999). The disclosure must be reviewed from the point of view of one skilled in the relevant art to determine whether that person would understand the written description to disclose the corresponding structure, material, or acts. Tech. Licensing Corp. v. Videotek, Inc., 545 F.3d 1316, 1338 (Fed. Cir. 2008); Med. Instrumentation & Diagnostics Corp. v. Elekta AB, 344 F.3d 1205, 1211-12 (Fed. Cir. 2003). To satisfy the definiteness requirement under 35 U.S.C. 112, second paragraph, the written description must clearly link or associate the corresponding structure, material, or acts to the claimed function. Telcordia Techs., Inc. v. Cisco Systems, Inc., 612 F.3d 1365, 1376 (Fed. Cir. 2010). A rejection under 35 U.S.C. 112, second paragraph is appropriate if the written description fails to link or associate the disclosed structure, material, or acts to the claimed function, or if there is no disclosure (or insufficient disclosure) of structure, material, or acts for performing the claimed function. Donaldson, 16 F.3d at 1195. A bare statement that known techniques or methods can be used would not be a sufficient disclosure to support a means-plus-function limitation. Biomedino, LLC v. Waters Techs. Corp., 490 F.3d 946, 953 (Fed. Cir. 2007).

A rejection under 35 U.S.C. 112, second paragraph may be appropriate in the following situations when examining means-plus-function claim limitations under 35 U.S.C. 112, sixth paragraph:

    • (1) when it is unclear whether a claim limitation invokes 35 U.S.C. 112, sixth paragraph;
    • (2) when 35 U.S.C. 112, sixth paragraph is invoked and there is no disclosure or there is insufficient disclosure of structure, material, or acts for performing the claimed function; and/or
    • (3) when 35 U.S.C. 112, sixth paragraph is invoked and the supporting disclosure fails to clearly link or associate the disclosed structure, material, or acts to the claimed function.

When the examiner cannot identify the corresponding structure, material, or acts, a rejection under 35 U.S.C. 112, second paragraph should be made. In some cases, a requirement for information under 37 CFR 1.105 may be made to require the identification of the corresponding structure, material, or acts. See MPEP § 704.11(a) (Example R). If a requirement for information under 37 CFR 1.105 is made and the applicant states that he or she lacks such information or the reply does not identify the corresponding structure, material, or acts, a rejection under 35 U.S.C. 112, second paragraph should be made. For more information, see MPEP § 704.12 ("Replies to requirements for information must be complete and filed within the time period set including any extensions. Failure to reply within the time period set will result in the abandonment of the application.")

If the written description sets forth the corresponding structure, material, or acts in compliance with 35 U.S.C. 112, second paragraph, the claim limitation must "be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof." 35 U.S.C. 112, sixth paragraph. However, functional limitations that are not recited in the claim, or structural limitations from the written description that are unnecessary to perform the claimed function, cannot be imported into the claim. Welker Bearing, 550 F.3d at 1097; Wenger Mfg., Inc. v. Coating Mach. Sys., Inc., 239 F.3d 1225, 1233 (Fed. Cir. 2001).

The following guidance is provided to determine whether applicant has complied with the requirements of 35 U.S.C. 112, second paragraph, when 35 U.S.C. 112, sixth paragraph, is invoked:

    • (A) If the corresponding structure, material or acts are described in the specification in specific terms (e.g., an emitter-coupled voltage comparator) and one skilled in the art could identify the structure, material or acts from that description, then the requirements of 35 U.S.C. 112, second and sixth paragraphs and are satisfied. See Atmel , 198 F.3d at 1382, 53 USPQ2d 1231.
    • (B) If the corresponding structure, material or acts are described in the specification in broad generic terms and the specific details of which are incorporated by reference to another document (e.g., attachment means disclosed in U.S. Patent No. X, which is hereby incorporated by reference, or a comparator as disclosed in the IBM article, which is hereby incorporated by reference), Office personnel must review the description in the specification, without relying on any material from the incorporated document, and apply the "one skilled in the art" analysis to determine whether one skilled in the art could identify the corresponding structure (or material or acts) for performing the recited function to satisfy the definiteness requirement of 35 U.S.C. 112, second paragraph. See Default Proof Credit Card System, Inc. v. Home Depot U.S.A., Inc., 412 F.3d 1291, 75 USPQ2d 1116 (Fed. Cir. 2005) ("The inquiry under [35 U.S.C.] § 112, ¶ 2, does not turn on whether a patentee has ‘incorporated by reference’ material into the specification relating to structure, but instead asks first ‘whether structure is described in the specification, and, if so, whether one skilled in the art would identify the structure from that description’").
      • (1) If one skilled in the art would be able to identify the structure, material or acts from the description in the specification for performing the recited function, then the requirements of 35 U.S.C. 112, second paragraph, are satisfied. See Dossel, 115 F.3d at 946-47, 42 USPQ2d at 1885 (The function recited in the means-plus-function limitation involved "reconstructing" data. The issue was whether the structure underlying this "reconstructing" function was adequately described in the written description to satisfy 35 U.S.C. 112, second paragraph. The court stated that "[n]either the written description nor the claims uses the magic word ‘computer,’ nor do they quote computer code that may be used in the invention. Nevertheless, when the written description is combined with claims 8 and 9, the disclosure satisfies the requirements of Section 112, Para. 2." The court concluded that based on the specific facts of the case, one skilled in the art would recognize the structure for performing the "reconstructing" function since "a unit which receives digital data, performs complex mathematical computations and outputs the results to a display must be implemented by or on a general or special purpose computer." ). See also Intel Corp. v. VIA Technologies, Inc, 319 F.3d 1357, 1366, 65 USPQ2d 1934, 1941 (Fed. Cir. 2003) (The "core logic" structure that was modified to perform a particular program was held to be adequate corresponding structure for a claimed function although the specification did not disclose internal circuitry of the core logic to show exactly how it must be modified.)
      • (2) If one skilled in the art would not be able to identify the structure, material or acts from description in the specification for performing the recited function, then applicant will be required to amend the specification to include the material incorporated by reference and to clearly link or associate the structure, material or acts to the function recited in the claim. Applicant should not be required to insert the subject matter described in the entire referenced document into the specification. To maintain a concise specification, applicant should only include the relevant portions of the referenced document that correspond to the means (or step)-plus-function limitation. See Atmel, 198 F.3d at 1382, 53 USPQ2d at 1230 ( "All one needs to do…is to recite some structure corresponding to the means in the specification…so that one can readily ascertain what the claim means and comply with the particularity requirement of Para. 2." ).

IV.   DETERMINING WHETHER 35 U.S.C. 112, FIRST PARAGRAPH SUPPORT EXISTS

The claims must still be analyzed to determine whether there exists corresponding adequate support for such claim under 35 U.S.C. 112, first paragraph. In considering whether there is 35 U.S.C. 112, first paragraph support for the claim limitation, the examiner must consider not only the original disclosure contained in the summary and detailed description of the invention portions of the specification, but also the original claims, abstract, and drawings. See In re Mott, 539 F.2d 1291, 1299, 190 USPQ 536, 542–43 (CCPA 1976) (claims); In re Anderson, 471 F.2d 1237, 1240, 176 USPQ 331, 333 (CCPA 1973) (claims); Hill-Rom Co. v. Kinetic Concepts, Inc., 209 F.3d 1337, 54 USPQ2d 1437 (Fed. Cir. 2000) (unpublished) (abstract); In re Armbruster, 512 F.2d 676, 678–79, 185 USPQ 152, 153–54 (CCPA 1975) (abstract); Anderson, 471 F.2d at 1240, 176 USPQ at 333 (abstract); Vas-Cath Inc. v. Mahurkar, 935 F.2d at 1564, 19 USPQ2d at 1117 (drawings); In re Wolfensperger, 302 F.2d 950, 955–57, 133 USPQ 537, 541– 43 (CCPA 1962) (drawings).

37 CFR 1.75 (d)(1) provides, in part, that "the terms and phrases used in the claims must find clear support or antecedent basis in the description so that the meaning of the terms in the claims may be ascertainable by reference to the description." In the situation in which the written description only implicitly or inherently sets forth the structure, materials, or acts corresponding to a means- (or step-) plus-function, and the examiner concludes that one skilled in the art would recognize what structure, materials, or acts perform the function recited in a means- (or step-) plus-function, the examiner should either: (A) have the applicant clarify the record by amending the written description such that it expressly recites what structure, materials, or acts perform the function recited in the claim element; or (B) state on the record what structure, materials, or acts perform the function recited in the means- (or step-) plus-function limitation. Even if the disclosure implicitly sets forth the structure, materials, or acts corresponding to a means- (or step-) plus-function claim element in compliance with 35 U.S.C. 112, first and second paragraphs, the USPTO may still require the applicant to amend the specification pursuant to 37 CFR 1.75 (d) and MPEP § 608.01(o) to explicitly state, with reference to the terms and phrases of the claim element, what structure, materials, or acts perform the function recited in the claim element. See 35 U.S.C. 112, sixth paragraph ("An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof." (emphasis added)); see also B. Braun Medical, 124 F.3d at 1424, 43 USPQ2d at 1900 (holding that "pursuant to this provision [35 U.S.C. 112,  sixth paragraph], structure disclosed in the specification is ‘corresponding’ structure only if the specification or prosecution history clearly links or associates that structure to the function recited in the claim. This duty to link or associate structure to function is the quid pro quo for the convenience of employing 112, paragraph 6."); Medical Instrumentation and Diagnostic Corp. v. Elekta AB, 344 F.3d 1205, 1218, 68 USPQ2d 1263, 1268 (Fed. Cir. 2003)(Although one of skill in the art would have been able to write a software program for digital to digital conversion, such software did not fall within the scope of "means for converting" images as claimed because nothing in the specification or prosecution history clearly linked or associated such software with the function of converting images into a selected format.); Wolfensperger, 302 F.2d at 955, 133 USPQ at 542 (just because the disclosure provides support for a claim element does not mean that the USPTO cannot enforce its requirement that the terms and phrases used in the claims find clear support or antecedent basis in the written description).

V.   SINGLE MEANS CLAIMS

Donaldson does not affect the holding of In re Hyatt, 708 F.2d 712, 218 USPQ 195 (Fed. Cir. 1983) to the effect that a single means claim does not comply with the enablement requirement of 35 U.S.C. 112, first paragraph. As Donaldson applies only to an interpretation of a limitation drafted to correspond to 35 U.S.C. 112, sixth paragraph, which by its terms is limited to "an element in a claim to a combination," it does not affect a limitation in a claim which is not directed to a combination. See also MPEP § 2164.08(a).

VI.   ENSURE THAT THE RECORD IS CLEAR

The examiner should specify in the Office action that a claim limitation has been interpreted under the provisions of 35 U.S.C. 112, sixth paragraph. When claim terms other than "means for" are determined to invoke 35 U.S.C. 112, sixth paragraph, the reasons why the claim was interpreted as invoking 35 U.S.C. 112, sixth paragraph, should also be clearly stated in the Office action. For example, the Office action can include a statement that a certain claim limitation is expressed in functional terms coupled to a non-structural word (e.g., "module for,") that does not connote structure and therefore invokes treatment under 35 U.S.C. 112, sixth paragraph. When the examiner has determined that 35 U.S.C. 112, sixth paragraph applies, the examiner may also specify what the specification identifies as the corresponding structure.

Additionally, if the corresponding structure for the claimed function is not clearly identifiable in the specification, the Office action should, nevertheless, attempt to identify what structure is most closely associated with the means-plus-function limitation to facilitate a prior art search. This is especially true when there may be confusion as to which disclosed implementation of the invention supports the limitation, as explained in section II.B above.

When allowing a claim that was treated under 35 U.S.C. 112, sixth paragraph, the examiner should indicate that the claim was interpreted under the provisions of 35 U.S.C. 112, sixth paragraph in reasons for allowance if such an explanation has not previously been made of record. As noted above, the indication should also clarify the associated structure if not readily apparent in the specification.