This PhEP describes the extension of Pharo numeric literals to accepts (and ignore) underscore characters (`_` ASCII 95).
Many languages (including Python https://peps.python.org/pep-0515/ , Java https://docs.oracle.com/javase/7/docs/technotes/guides/language/underscores-literals.html or Ruby) accept some forms of numeric literal that ignore _. The idea is to permit long literals that are still readable, eg. `1_000_000_000` is easier for a human than `100000000` especially since in the previous literal a zero is missing (I'm a tricky deceitful fellow). The details of the proposal are in the PR: https://github.com/pharo-project/pheps/pull/16 -- Jean Privat
