Locating DB Tables/Fields

Do you know about Ctrl-Shift-O ?
In Portal, position your cursor into the field that you have questions about and perform the Ctrl-Shift-O.
The field name should appear in your IE status bar.

The expense account is in the ICCATEGORY table - it's tied to the GL Category on IC12. The Vendor and Purchase From Location is in the ITEMSRC table.

Note: when performing ctrl-shift-o, the information returned contains the table abbreviation then a dash and then the field name.
ie: Purchase from: ITM-PURCH-FRM-LOC --- ITM means the ITEMSRC table, then the field is PURCH-FRM-LOC

Our report writers here, have found a script I wrote particularly helpful too. If you are on Windows, you can perform the steps manually, I suppose? It's just making use of some of the Lawson utilities.
I'll attach it here, and if you have any questions, please post back.

You can get a listing of your table abbreviations by:
rngdbdump -cnt gen filedef -f Prefix FileName SystemCode | sort

Problem solved, knowledge increased. Thanks to you both!