PTAB says "identifying a number of patients" requires identification of a group but not a specific number

In a post from earlier this year – When does "a" mean "the" – I  discussed the meaning of "A number of" as used in a claim. As I noted in that post, typical English usage would be "THE number of widgets" but because THE has a special meaning in claim language, drafters sometimes rephrase as "A number of widgets".

The earlier post was about two Board decisions that considered whether this phrase was indefinite, since the phrase was amenable to two interpretations. One decision said indefinite, one said not indefinite.

I've found another decision in which the Board came at this phrase from a different angle – claim construction rather than indefiniteness.

In Ex parte Scherpbier, the claim limitation read "identifying a first number of patients at a particular location awaiting processing at a particular treatment process stage." The Applicant argued that the prior art did not identify the actual number in the phrase “a … number of patients.” The Board said the claim did not require this.

     ... The issue here is the proper interpretation of this phrase. Unfortunately, Appellants chose an English language idiom generally referring to an indefinite group of patients for this limitation. In the face of a limitation susceptible to plural reasonable interpretations, the Office may test each interpretation against the art, because “[i]t is the applicants’ burden to precisely define the invention, not the PTO’s.” In re Morris, 127 F.3d 23 1048, 1056 (Fed. Cir. 1997).
     Although it is possible to interpret the claim as identifying the actual numeric total of such patients, it is equally proper to interpret the claim as identifying some indefinite group of patients. [Indirect reference to definition from McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.] The art clearly identifies such an indefinite group, and this is how the Examiner interpreted the claim phrasing.
     Given no clear exclusion of such an interpretation in the claim, we find the Examiner’s construction reasonable in view of the ordinary and customary idiomatic usage of this phrasing and the art describes such identification. 

The Board did not enter a new indefiniteness rejection.