MPEP 2181

2181 Identifying a 35 U.S.C. 112, Sixth Paragraph Limitation

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.

I. LANGUAGE FALLING WITHIN 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. Applicants before the USPTO have the opportunity and the obligation to define their inventions precisely during proceedings before the PTO.

Applicants and reexamination patentees before the USPTO have an opportunity and obligation to specify, consistent with these guidelines, when a claim limitation invokes 35 U.S.C. 112, sixth paragraph.

A claim limitation will be presumed to invoke 35 U.S.C. 112, sixth paragraph, if it meets the following 3-prong analysis:

(A) the claim limitations must use the phrase “means for” or “step for;”

(B) the “means for” or “step for” must be modified by functional language; and

(C) the phrase “means for” or “step for” must not be modified by sufficient structure, material, or acts for achieving the specified function.

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 considered to invoke 35 U.S.C. 112, sixth paragraph. If 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” in accordance with these guidelines; or (B) show that even though the phrase “means for” or “step for” is not used, the claim limitation is written as a function to be performed and does not recite sufficient structure, material, or acts which would preclude application of 35 U.S.C. 112, sixth paragraph.

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.

Cases:

• 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”).
• Al-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).
• 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’”).
• 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 an express recitation of “means for” or “step for” in the limitation, the broadest reasonable interpretation will not be limited to “corresponding structure…and equivalents thereof.”
• In re Morris, 127 F.3d 1048, 1056-57, 44 USPQ2d 1023, 1029-30 (Fed. Cir. 1997)(“no comparable mandate in the patent statute that relates the claim scope of non-§ 112paragraph 6 claims to particular matter found in the specification”).

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.

Cases:

• 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).).

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). Also, a statement of function appearing only in the claim preamble is generally insufficient to invoke 35 U.S.C. 112, sixth paragraph.

With respect to the third prong of this analysis, 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.

Cases:

• 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).

If the phrase “means for” or “step for” 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. 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.

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. However, if a claim limitation does not use the phrase “means for” or “step for,” that is, the first prong of the 3-prong analysis is not met, the examiner will not treat such a claim limitation under 35 U.S.C. 112, sixth paragraph. It will not be necessary to state in the Office action that 35 U.S.C. 112, sixth paragraph, has not been invoked, since the presumption is that applicant did not intend to invoke the provisions of 35 U.S.C. 112, sixth paragraph, because applicant did not use the specific phrase “means for” or “step for.” If a claim limitation does include the phrase “means for” or “step for,” that is, the first prong of the 3-prong analysis is met, 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.

Accordingly, these guidelines provide applicants with the opportunity to either invoke or not invoke 35 U.S.C. 112, sixth paragraph, based upon a clear and simple set of criteria.

The following examples illustrate additional situations where the phrase “means for” or “step for” was not used but the Board or the courts determined that the claim limitation falls 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 serules. As noted above, examiners should apply the 3- prong analysis to determine whether the claim limitation will be interpreted to invoke 35 U.S.C. 112, sixth paragraph. A claim element that does not include the phrase “means for” or “step for” will not be considered to invoke 35 U.S.C. 112, sixth paragraph. If an applicant wishes to have the claim limitation treated under 35 U.S.C. 112, sixth paragraph, applicant must either amend the claim to include the phrase “means for” or “step for,” or show that even though the phrase “means for” or “step for” is not used, the claim limitation is written as a function to be performed and does not recite sufficient structure, material, or acts which would preclude application of 35 U.S.C. 112, sixth paragraph.

(A)a jet driving device so constructed and located on the rotor as to drive the rotor . . . [“means” unnecessary]. The term “device” coupled with a function is a proper definition of structure in accordance with the last paragraph of 35 U.S.C. 112. The addition of the words “jet driving” to the term “device” merely renders the latter more definite and specific. Ex parteStanley, 121 USPQ 621 (Bd. App. 1958);

(B)“printing means” and “means for printing” which would have the same connotations. Ex parteKlumb, 159 USPQ 694 (Bd. App. 1967). However, the terms “plate” and “wing,” as modifiers for the structureless term “means,” specify no function to be performed, and do not fall under the last paragraph of 35 U.S.C. 112;

(C)force generating means adapted to provide . . . . De Graffenreid v. United States, 20 Ct. Cl. 458, 16 USPQ2d 1321 (Ct. Cl. 1990);

(D)call cost register means, including a digital display for providing a substantially instantaneous display for . . . . Intellicall Inc. v. Phonometrics, Inc., 952 F.2d 1384, 21 USPQ2d 1383 (Fed. Cir. 1992);

(E)reducing the coefficient of friction of the resulting film [step plus function; “step” unnecessary], In re Roberts, 470 F.2d 1399, 176 USPQ 313 (CCPA 1973); and

(F)raising the pH of the resultant pulp to about 5.0 to precipitate . . . . Ex parte Zimmerley, 153 USPQ 367 (Bd. App. 1966).

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. WRITTEN 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).

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. Budde 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). However, 35 U.S.C. 112, sixth paragraph, does not impose any requirements in addition to those imposed by 35 U.S.C. 112, first paragraph. See In re Knowlton, 481 F.2d 1357, 1366, 178 USPQ 486, 492– 93 (CCPA 1973). Conversely, 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; Knowlton, 481 F.2d at 1366, 178 USPQ at 493.

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). Rather, 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.)”).

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

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 reHyatt, 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).