In the Sage 50 version, there is an additional field available across all transaction types, at the line item level / transaction level - "Ex.Ref."  This field is also searchable.

A common example where this would be used:

Say we attend a trade show, "ABC Show."  We would like to see all the related costs for this show, whether paid by Credit Card, Check, Employee reimbursable expense, time, etc.

Then we can search for "ABC Show" and see all related expenses and costs for that trade show event.

I have spoken to Sage and there is not a comparable field that runs across all transaction types, but if someone has a solution, that would be great.