MPEP 2173.05(b)
Relative Terminology

Ninth Edition of the MPEP, Revision 07.2022, Last Revised in February 2023

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2173.05(b)    Relative Terminology [R-07.2022]

The use of relative terminology in claim language, including terms of degree, does not automatically render the claim indefinite under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. Seattle Box Co., Inc. v. Industrial Crating & Packing, Inc., 731 F.2d 818, 221 USPQ 568 (Fed. Cir. 1984). Acceptability of the claim language depends on whether one of ordinary skill in the art would understand what is claimed, in light of the specification.


Terms of degree are not necessarily indefinite. "Claim language employing terms of degree has long been found definite where it provided enough certainty to one of skill in the art when read in the context of the invention." Interval Licensing LLC v. AOL, Inc., 766 F.3d 1364, 1370, 112 USPQ2d 1188, 1192-93 (Fed. Cir. 2014) (citing Eibel Process Co. v. Minnesota & Ontario Paper Co., 261 U.S. 45, 65-66 (1923) (finding ‘substantial pitch’ sufficiently definite because one skilled in the art ‘had no difficulty … in determining what was the substantial pitch needed’ to practice the invention)). Thus, when a term of degree is used in the claim, the examiner should determine whether the specification provides some standard for measuring that degree. Hearing Components, Inc. v. Shure Inc., 600 F.3d 1357, 1367, 94 USPQ2d 1385, 1391 (Fed. Cir. 2010); Enzo Biochem, Inc., v. Applera Corp., 599 F.3d 1325, 1332, 94 USPQ2d 1321, 1326 (Fed. Cir. 2010); Seattle Box Co., Inc. v. Indus. Crating & Packing, Inc., 731 F.2d 818, 826, 221 USPQ 568, 574 (Fed. Cir. 1984). If the specification does not provide some standard for measuring that degree, a determination must be made as to whether one of ordinary skill in the art could nevertheless ascertain the scope of the claim (e.g., a standard that is recognized in the art for measuring the meaning of the term of degree). For example, in Ex parte Oetiker, 23 USPQ2d 1641 (Bd. Pat. App. & Inter. 1992), the phrases "relatively shallow," "of the order of," "the order of about 5mm," and "substantial portion" were held to be indefinite because the specification lacked some standard for measuring the degrees intended.

The claim is not indefinite if the specification provides examples or teachings that can be used to measure a degree even without a precise numerical measurement (e.g., a figure that provides a standard for measuring the meaning of the term of degree). See, e.g., Interval Licensing LLC v. AOL, Inc., 766 F.3d 1364, 1371-72, 112 USPQ2d 1188, 1193 (Fed. Cir. 2014) (observing that although there is no absolute or mathematical precision required, "[t]he claims, when read in light of the specification and the prosecution history, must provide objective boundaries for those of skill in the art").

During prosecution, an applicant may also overcome an indefiniteness rejection by providing evidence that the meaning of the term of degree can be ascertained by one of ordinary skill in the art when reading the disclosure. For example, in Enzo Biochem, the applicant submitted a declaration under 37 CFR 1.132 showing examples that met the claim limitation and examples that did not. Enzo Biochem, 599 F.3d at 1335, 94 USPQ2d at 1328 (noting that applicant overcame an indefiniteness rejection over "not interfering substantially" claim language by submitting a declaration under 37 CFR 1.132 listing eight specific linkage groups that applicant declared did not substantially interfere with hybridization or detection).

Even if the specification uses the same term of degree as in the claim, a rejection is proper if the scope of the term is not understood when read in light of the specification. While, as a general proposition, broadening modifiers are standard tools in claim drafting in order to avoid reliance on the doctrine of equivalents in infringement actions, when the scope of the claim is unclear a rejection under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph, is proper. See In re Wiggins, 488 F. 2d 538, 541, 179 USPQ 421, 423 (CCPA 1973).

When relative terms are used in claims wherein the improvement over the prior art rests entirely upon size or weight of an element in a combination of elements, the adequacy of the disclosure of a standard is of greater criticality.


A claim may be rendered indefinite when a limitation of the claim is defined by reference to an object and the relationship between the limitation and the object is not sufficiently defined. That is, where the elements of a claim have two or more plausible constructions such that the examiner cannot readily ascertain positional relationship of the elements, the claim may be rendered indefinite. See, e.g., Ex parte Miyazaki, 89 USPQ2d 1207 (Bd. Pat. App. & Inter. 2008) (precedential) and Ex parte Brummer, 12 USPQ2d 1653 (Bd. Pat. App. & Inter. 1989). In Miyazaki, the Board held that claims to a large printer were not sufficiently definite because:

The language of claim 1 attempts to claim the height of the paper feeding unit in relation to a user of a specific height who is performing operations on the printer.... Claim 1 fails to specify, however, a positional relationship of the user and the printer to each other.

Miyazaki, 89 USPQ2d at 1212. In Brummer, the Board held that a limitation in a claim to a bicycle that recited "said front and rear wheels so spaced as to give a wheelbase that is between 58 percent and 75 percent of the height of the rider that the bicycle was designed for" was indefinite because the relationship of parts was not based on any known standard for sizing a bicycle to a rider, but on a rider of unspecified build. Brummer, 12 USPQ2d at 1655.

On the other hand, a claim limitation specifying that a certain part of a pediatric wheelchair be "so dimensioned as to be insertable through the space between the doorframe of an automobile and one of the seats" was held to be definite. Orthokinetics, Inc. v. Safety Travel Chairs, Inc., 806 F.2d 1565, 1 USPQ2d 1081 (Fed. Cir. 1986). The court stated that the phrase "so dimensioned" is as accurate as the subject matter permits, noting that the patent law does not require that all possible lengths corresponding to the spaces in hundreds of different automobiles be listed in the patent, let alone that they be listed in the claims.


A.    "About"

In determining the range encompassed by the term "about", one must consider the context of the term as it is used in the specification and claims of the application. Ortho-McNeil Pharm., Inc. v. Caraco Pharm. Labs., Ltd., 476 F.3d 1321, 1326, 81 USPQ2d 1427, 1432 (Fed. Cir. 2007). InW.L. Gore & Associates, Inc. v. Garlock, Inc., 721 F.2d 1540, 220 USPQ 303 (Fed. Cir. 1983), the court held that a limitation defining the stretch rate of a plastic as "exceeding about 10% per second" is definite because infringement could clearly be assessed through the use of a stopwatch. However, in another case, the court held that claims reciting "at least about" were invalid for indefiniteness where there was close prior art and there was nothing in the specification, prosecution history, or the prior art to provide any indication as to what range of specific activity is covered by the term "about." Amgen, Inc. v. Chugai Pharmaceutical Co., 927 F.2d 1200, 18 USPQ2d 1016 (Fed. Cir. 1991).

B.    "Essentially"

The phrase "a silicon dioxide source that is essentially free of alkali metal" was held to be definite because the specification contained guidelines and examples that were considered sufficient to enable a person of ordinary skill in the art to draw a line between unavoidable impurities in starting materials and essential ingredients. In re Marosi, 710 F.2d 799, 218 USPQ 289 (CCPA 1983). The court further observed that it would be impractical to require applicants to specify a particular number as a cutoff between their invention and the prior art.

C.    "Similar"

The term "similar" in the preamble of a claim that was directed to a nozzle "for high-pressure cleaning units or similar apparatus" was held to be indefinite since it was not clear what applicant intended to cover by the recitation "similar" apparatus. Ex parte Kristensen, 10 USPQ2d 1701 (Bd. Pat. App. & Inter. 1989).

A claim in a design patent application which read: "The ornamental design for a feed bunk or similar structure as shown and described." was held to be indefinite because it was unclear from the specification what applicant intended to cover by the recitation of "similar structure." Ex parte Pappas, 23 USPQ2d 1636 (Bd. Pat. App. & Inter. 1992).

D.    "Substantially"

The term "substantially" is often used in conjunction with another term to describe a particular characteristic of the claimed invention. It is a broad term. In re Nehrenberg, 280 F.2d 161, 126 USPQ 383 (CCPA 1960). The court held that the limitation "to substantially increase the efficiency of the compound as a copper extractant" was definite in view of the general guidelines contained in the specification. In re Mattison, 509 F.2d 563, 184 USPQ 484 (CCPA 1975). The court held that the limitation "which produces substantially equal E and H plane illumination patterns" was definite because one of ordinary skill in the art would know what was meant by "substantially equal." Andrew Corp. v. Gabriel Electronics, 847 F.2d 819, 6 USPQ2d 2010 (Fed. Cir. 1988).

E.    "Type"

The addition of the word "type" to an otherwise definite expression (e.g., Friedel-Crafts catalyst) extends the scope of the expression so as to render it indefinite. Ex parte Copenhaver, 109 USPQ 118 (Bd. Pat. App. & Inter. 1955). Likewise, the phrase "ZSM-5-type aluminosilicate zeolites" was held to be indefinite because it was unclear what "type" was intended to convey. The interpretation was made more difficult by the fact that the zeolites defined in the dependent claims were not within the genus of the type of zeolites defined in the independent claim. Ex parte Attig, 7 USPQ2d 1092 (Bd. Pat. App. & Inter. 1986).



When a subjective term is used in the claim, the examiner should determine whether the specification supplies some standard for measuring the scope of the term, similar to the analysis for a term of degree. Some objective standard must be provided in order to allow the public to determine the scope of the claim. A claim that requires the exercise of subjective judgment without restriction may render the claim indefinite. In re Musgrave, 431 F.2d 882, 893, 167 USPQ 280, 289 (CCPA 1970). Claim scope cannot depend solely on the unrestrained, subjective opinion of a particular individual purported to be practicing the invention. Datamize LLC v. Plumtree Software, Inc., 417 F.3d 1342, 1350, 75 USPQ2d 1801, 1807 (Fed. Cir. 2005)); see also Interval Licensing LLC v. AOL, Inc., 766 F.3d 1364, 1373, 112 USPQ2d 1188 (Fed. Cir. 2014) (holding the claim phrase "unobtrusive manner" indefinite because the specification did not "provide a reasonably clear and exclusive definition, leaving the facially subjective claim language without an objective boundary").

For example, in Datamize, the invention was directed to a computer interface screen with an "aesthetically pleasing look and feel." Datamize, 417 F.3d at 1344-45, 75 USPQ2d at 1802-03. The meaning of the term "aesthetically pleasing" depended solely on the subjective opinion of the person selecting features to be included on the interface screen. Nothing in the intrinsic evidence (e.g., the specification) provided any guidance as to what design choices would result in an "aesthetically pleasing" look and feel. 417 F.3d at 1352, 75 USPQ2d at 1808. The claims were held indefinite because the interface screen may be "aesthetically pleasing" to one user but not to another. 417 F.3d at 1350, 75 USPQ2d at 1806. See also Ex parte Anderson, 21 USPQ2d 1241 (Bd. Pat. App. & Inter. 1991) (the terms "comparable" and "superior" were held to be indefinite in the context of a limitation relating the characteristics of the claimed material to other materials).

During prosecution, the applicant may overcome a rejection by amending the claim to remove the subjective term, or by providing evidence that the meaning of the term can be ascertained by one of ordinary skill in the art when reading the disclosure. However, "[f]or some facially subjective terms, the definiteness requirement is not satisfied by merely offering examples that satisfy the term within the specification." DDR Holdings, LLC v., L.P., 773 F.3d 1245, 1261, 113 USPQ2d 1097, 1108 (Fed. Cir. 2014).