Very useful starting point.  Thank you very much.

It does turn out that the tables are in TABLES.W0 (for 2020) rather than .IW0.  I copied out TABLES.W0 to another location, renamed the extension as .ZIP, and that allowed me to extract the files in which I found, among dozens of files, @I_14_800 which was a text file containing all the employer data within my client universe and @F_12_800 which was a text file containing the bank/broker data.

Is there a document directory for these table files?

Now on to trying to parse out my current data!