Valid signal names

["Alexandre Moreira" <alexandream gmail com>]

Ok, this is probably some dumb newbie question, but I couldn't find
this on the internet (and I did search it).

What can make a valid signal name ? I've seen the alphanumeric
characters and the hyphen in the docs but, could I possibly create a
signal name with dots, like in "org.domain.appname.signal" if I want
to prefix it ?

Again, is there a maximum length for signal names ?

Regards,
Alexandre Moreira.