J1 is most likely the joist mark that refers to the shop drawings. The other numbers don't mean anything to me unless it is perhaps a special joist with load info.
Some joists have multiple tags. You may have to look at all of them, although I have usually found that the metal tag is the one that you want. The other tag(s) may be for painting info.
I suggest you check all tags and examine adjacent joists. You should be able to find the info. that you need.