This is actually a general question, and I highly recommend that you consider the SVNBook chapter, “Ignoring Unversioned Items,” which covers it.
See an important excerpt from SVNBook that explains the behavior:
Subversion . Subversion, . , Subversion, , pattern-Subversion .
svn status (, '?') (, '!').
? something.aux
! somethingelse.aux
, (.. Windows, SVN) somethingelse.aux, "". something.aux .
svn propset, , , :
, svn: ignore, , , - .
svn:ignore, svn propget.