Rockwell - I am looking at my husband's dog tags. The one he was issued here in the United States when he was an enlisted man have his name, SN, my name and his home town. The home town probably was the address he gave when he enlisted. No notation of religous preference or tetanus shot.
When he became an officer the tag has the same info plus an O for blood type and his religous preference indicated by a P as well as my name now listed as ME Ellison instead of Mary.
When he was overseas the tag has his name, SN, date of tetanus shot, O for blood type and P for religous preference.
There was some discussion about having the J for Judism for the Jewish soldiers because the Germans were often not nice to Jewish prisoners. However when the preference was left blank the Germans still assumed the man Jewish and were apt to mistreat him. I do not know how that was cared for except that I have heard of Jewish prisoners who were mistreated. I don't know the origin of that info.