It's JCL not C

True Story from a long time ago

So a LONG time ago, 1980s, I used to work on MVS OS\370 mainframes, coding in COBOL and controlling with JCL.

Flash forward a few years, other languages come along and I am really enjoying working in C.

Some project team needed some old stuff supported and knew I was considered very good/an expert on the older systems so, I was asked to provide some support, so I took a look at the JCL. It looked something like

//JOBNAME JOB CLASS=A   
//STEP1 EXEC PGM=MYPROGA
//SYSIN DD   HEREISAFILE
//STEP2      DOSOMETHING
...etc 

The first thought that came to me is why is all this JCL commented out ... of course it wasn't, I'd just been working on C too long and old stuff a long time ago. By this time // was commonly used for comments in C but of course in JCL it just signifies the beginning of a job step ... Seriously, my brain took a few mins to switch!

See this punchcard for an interesting encoding.