[DrScump]

Aside from the physical encoding, note the conventions for IBM tape file sequence and labeling:

https://www.ibm.com/docs/en/zvse/6.2?topic=SSB27H_6.2.0/fa2m...

You can bypass default label assumptions and label processing using JCL directives like BLP, NL, etc.

When I was in mainframe operations and at times ran the Production Control Center (triage), I rescued some systems from being rerun due to clobbered labels by altering JCL.

[passer_byer]

This is very helpful. I’m guessing you have a copy of the Brown/Blue => Blue/Brown book.

[DrScump]

I'm not familiar with that description. I worked as a 370 series (370/3033/308x/309x) OS/MVS computer operator in the 80s, before programming.

[raarts]

I worked as an 370 ACP/TPF Assembly Language Programmer in the 80s. I think this is referring to Gary DeWard Brown who wrote books about assembly language and JCL for example. Don't remember if they were blue though.

[passer_byer]

Gary deWard Brown is the author and hence the name. If I recall, he also describes utilities like IEBGENER, IEBCOPY and so on.

One copy of the book on Amazon was over $100.