We now use svn:keywords "Id" on all .c/.cpp/.h/.sp/.inc files.  Please make sure your client is configured properly.  

WINDOWS:
 Open your Application Data folder.  
 Windows XP/2000:	C:\Documents and Settings\<user>\Application Data
 Windows Vista:		C:\Users\<user>\AppData\Roaming

 Now go to Subversion.  Open the "config" file with a text editor.

LINUX: 
 Open ~/.subversion/config with your favorite text editor.

Under [miscellany], uncomment this line:
# enable-auto-props = yes

Under [auto-props], add these lines:
*.c = svn:keywords=Id
*.cpp = svn:keywords=Id
*.h = svn:keywords=Id
*.sp = svn:keywords=Id
*.inc = svn:keywords=Id
