The /p4/common/site directory is to be used by SDP customers as an installed as a standard location for creating custom, site-specific SDP overrides. The automated SDP upgrade procedure will know to ignore in the /p4/common/site directory tree. The standard SDP shell environment mechanism includes /p4/common/site/bin in the PATH, so that adding executable files in where will make them easily accessible. Files in the /p4/common/site tree are inherently custom and site-local, and as such are not supported by Perforce Support.