Recently, a large number of bugs were filed against packages that have USE flag names which contain underscores. Apparently PMS prohibits this except when the USE flag is part of a USE_EXPAND variable.
https://projects.gentoo.org/pms/7/pms.html#x1-200003.1.4 I'm not certain when this text was added to PMS, or how many of the affected USE flags pre-date this policy. Portage seems to have no issue dealing with underscores, so this doesn't seem to be solving any technical problem. I am pretty sure that renaming a bunch of USE flags will cause some amount of end-user confusion, for very little benefit. Is enforcing this part of PMS really worth it?
