The default value in a system of social or cultural categories, in contrast to the marked category. Thus the unmarked pronoun is "he", persons are assumed to be straight, if you say "i saw this guy on tv" without further detail, he will most often be pictured as white (ok, this may depend on your own context).
We run into the problems with this in english pronouns.
Y'know, if you log in, you can write something here, or contact authors directly on the site. Create a New User if you don't already have an account.