Is it acceptable to reference limitations from another claim?

Yes, referencing limitations from another claim is generally acceptable. According to MPEP 2173.05(f):

“A claim which makes reference to a preceding claim to define a limitation is an acceptable claim construction which should not necessarily be rejected as improper or confusing under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph.”

This means that patent applicants can refer to limitations in other claims without automatically causing indefiniteness issues.

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Topics: MPEP 2100 - Patentability, MPEP 2173.05(F) - Reference To Limitations In Another Claim, Patent Law, Patent Procedure
Tags: 35 U.S.C. 112(B), Claim Construction, Claim Limitations, Claim Referencing