Target selector arguments x, y, z, r doesn't work alone.

What I did: Entered the command /gamemode c @a[0,4,0,5]
What I expected: all players within 5 blocks of 0,64,0 will be affected as mentioned on the wiki.
What happened: The following error: Invalid selector argument '0' .

Note: This still works: /gamemode c @a[x=0,y=4,z=0,r=5]