Distribution Name Constraint

Following a pgxn-users discussion, I’m looking at adding a constraint on the names distributions can have. I’m thinking this:

CREATE DOMAIN namespace AS CITEXT
CHECK ( VALUE ~ '^[-a-z0-9_]{2,}$' );

So, just ASCII numbers and letters, dash, and underscore, with a minimum length of two characters. Maybe , and + should be allowed, too? What do you think? What constraints do you expect on distribution download file names?