I see the "Label Field" information on page 85 of the most recent DFSORT Application Programming Guide. I understand the syntax of labels, but I'm having a difficult time understanding their purpose. Do labels serve any programmatic function? Or do they essentially serve as documentation only?
Labels just serve as documentation. I believe the original intent was to make the DFSORT control statements look like Assembler statements, e.g.
label operator operands remarks
but I don't see a good reason for them either and they introduce some "gotchas":
Labels are NOT allowed in control statements in DFSPARM or in the parameter lists. And because of labels, the operator cannot start in column 1. People often code the operator in column 1 leading to a syntax error message.
This was all decided about a decade before I joined the sort group by the original developers from Sweden - we're still stuck with it for compatability reasons.
When I designed the new syntax for ICETOOL, I did NOT allow labels and I did allow the operator to start in column 1.
>This was all decided about a decade before I joined the sort group by the original developers from Sweden<
Ja, dat explains eet.
I had also been looking for an ISPF HILITE language that seemed appropriate for DFSORT/ICETOOL control cards. Your explanation of the history explains why that's tricky; the DFSORT and ICETOOL syntaxes were developed independently.