Currently, / # : = are allowed. Add _ to that list.
Requiring a special character at the end of the IRI at all is sensible because it prevents registering namespaces where the final special character is accidentally missing, like a missing required #. But I don't see a benefit in keeping the list of allowed terminal characters particularly narrow. So, adding _ to the allowed terminals seems fine to me.
Example:
http://purl.obolibrary.org/obo/GO_
Currently,
/ # : =
are allowed. Add_
to that list.Requiring a special character at the end of the IRI at all is sensible because it prevents registering namespaces where the final special character is accidentally missing, like a missing required
#
. But I don't see a benefit in keeping the list of allowed terminal characters particularly narrow. So, adding_
to the allowed terminals seems fine to me.