Hi Gary,
The problem is that the jobs&customer fields do not really have a directly corresponding fields in IPTC/XMP so you'll basically have to find uses for them yourself.
For example, I use {clientcustom1} for the customer ID (four digit number) I give all my customers. I use this when ingesting to get the files in the right folder. E.g., folder name in the ingest dialog is set to: Commissioned/{clientcustom1} {clientcompany}/{jobname}
Note: the other fields I actually do not really use at all as metadata…
Cheers,
Hayo