ancient symax plc

hello again fellows. i have been tasked with upgrading some symax 400 processors to a new plc and i have been going through the logic and i am not sure about some of the functions i am seeing and am wondering if there is somebody out there that may can lend some advice. i have "GOSUB" functions which i believe to be like a jsr in new plc but that has a number associated with it that becomes unclear. i also have some "MARK" functions and i have no idea what those are. any advice is surely appreciated. i am trying to do this upgrade with no drawings or prints and half the wires going to the plc arent labeled either so i have my work cut out for me. and on top of that i cant find any good info on some of these instructions. Thanks.

I know next to nothing about this processor but did find an old post with a link that I made to a manual for the Symax400. Maybe there is something in the manual that will help.
Link:
http://www.plctalk.net/qanda/showpost.php?p=618485&postcount=17
I "might" have access to some old software also if that will help.

I have a paper manual for a SYMAX, but I cannot remember the model. Let me know if you are still stuck, and i can dig it out.