The below is an explanation of the how to setup a formula in the tran code basis field.
all tables start with _app.qas
_app.qpr.sql = "select * from dbo.property"
_app.qtr.sql = "select * from dbo.tran_file where id = :pidn and calc_type <> 'Paid'"
_app.qsv.sql = 'select * from dbo.service where pidn = :id and service = :tran_code'
_app.qtc.sql = 'select * from dbo.tranctl where tran_code = :tran_code'
_app.qas.sql = 'select * from dbo.assess where pidn = :id and tax_year = :tax_year'
*In your trancodes, Vance adds the Where stuff above behind the scene to make it work.
To get a value this is what your tran code looks like: