I'm trying to filter a query with the location field from a transaction, sales order in this case. everything I am trying isn't working, similar to Robert above, get a notification about the field being removed when trying transaction.location. Is there a way to do this?

I've pulled location from transactionline instead.

The aim was to use it at transaction level in the WHERE clause

Yeah, I use the MAX function. Since all our lines on any given transaction have the same location, any summary function applies to the transaction level.

Join to transactionline where mainline is T to get the transaction level location

ah, perfect. Didn't notice mainline was available