UML 2.5 uses lots of standard stereotypes and they are all typeset somehow (camel case seems to be default). But: it the casing relevant? There are only two occurrences of uppercase and lowercase in the whole document. Neither refers to stereotype (or keyword) usage.
I found it in the specs for UML 2.5 at page 260:
Normally a Stereotype’s name starts with an upper-case letter, to follow the convention for naming Classes. However Profiles may use different conventions. Matching between the names of Stereotype definitions and applications is case-insensitive, so naming stereotype applications with lower-case letters where the stereotypes are defined using upper-case letters is valid, although stylistically obsolete. For legacy reasons a tool may display stereotype names with the initial letter in lower case even when defined in upper case.
Stereotypes are case-insensitive