entering uid/pwd at console -- lower case uid/pwd interchageable with upper case

["Matthew L. Shobe" <mls_(_at_)_shobe_(_dot_)_org>]

While in #OpenBSD on Freenode, nate ( at ) ocalafl.net noticed that
a uid/pwd of a single case, (e.g. ``mls'', ``foobar1'',) can be
entered at ttyC? in upper case and authenticated, (e.g. ``MLS'',
``FOOBAR1'',) which seems a little... strange. Neither the manpages
for login(1), getpass(3), or readpassphrase(3), nor MARC or Google
shed light on why login's behavior might differ our expectations.
Might anyone spare a clue?
-- 
mls