The grammar does not cover the case with underscores between the digits of a Decimal. ThePEP-515 introduced underscores for integers, floating-point numbers and decimals. The documentation for integers and floating-point numbers are updated to cover underscores, but the grammar documentation for theDecimal does not.

Linked PRs

• gh-128185: Align the grammar of theDecimal string constructor withfloat's #128315
• gh-128185: align Decimal docs with spec (case irrelevant for nan/inf's) #128323
• [3.13] gh-128185: Align Decimal docs with spec (case irrelevant for nan/inf) (GH-128323) #132875