Some FreeBSD pkg_add Magic

In a recent comment a reader asked how he could install xorg 7.2 instead of xorg 6.9 on his FreeBSD 6.2 system. Normally pkg_add would do this, but xorg was updated to 7.2 after the release of FreeBSD 6.2, so the default behaviour is to install the version of xorg (6.9) which matches the release of the operating system. The answer is easy, but a bit of background information is useful.