Method to determine the earliest VRM source can be saved to?

[Dan <dan27649@xxxxxxxxx>]

I am writing a quickie app to backup source files with the intent that they
should be able to be restored to the earliest version possible.  In essence,
I'd like the TGTRLS parameter to allow an *EARLIEST or *OLDEST value.

It's true, while I'm on V5R2, I know what the earliest release TGTRLS will
accept.  But I would rather not have to modify the program for each release
upgrade we go through.

Best I can figure is to write a quickie command that will create a savefile
and an object to save in QTEMP, use SAVOBJ on that, starting at the earliest
release (say, start at V4R1, just for proof of concept), using MONMSG to
catch an invalid value for TGTRLS and looping up to try another.  Repeat
until find a valid VRM.

Is there a better way to make this determination?

TIA,
Dan