Okay, presuming they're not wanting you to go out and learn their mainframe and learn COBOL (your questions indicate you are not versed in either):
1) the file name is what is called a GDG (generational data set) and the (0) part represents the latest generation.
2) If you can find someone there who is versed with the mainframe enough to access both files for you and then download them to your workstation PC (the next step since you only use PC based languages), that would perhaps be best, since I have no idea of what that process would be where you are at. I presume you would need this, since you list predominantly pc based (not mainframe) languages and would need the files on your PC. Or am I mistaken?
3) There is an EBCDIC to ASCII conversion that is required. If you were to download the file without doing this first, it would mangle the data. This would require someone who is versed on the mainframe side to change the file around so you can read it on the PC side.
To borrow a searched post from WMK on this site (16 Mar 05 1:28):
1) All data should be USAGE DISPLAY (no COMP-3, COMP, BINARY, or PACKED-DECIMAL)
2) All numeric data should be defined with the SIGN IS SEPARATE clause
3) The output file should be defined (in the COBOL program) with the CODE-SET clause specifying STANDARD-1 (ASCII)
4) The JCL for the tape output file should include the
DCB=(OPTCD=Q) feature.
Someone there who is knowledgable in the mainframe should be able to understand all this if they don't know already how to get the file to your PC to work on. Otherwise, I'm not sure what advice I could give, unless some clarification can be sought on what they're expecting out of you (a mainframe program, or a PC program, or just simply some results regarding the file).
Once you have both files available to you in a way that can be used by your software, feel free to post the data definitions and we can help on those.