Tryton application platform - purchase secondary unit module

 Tryton is a high-level general purpose application platform. It is the base
 of a complete business solution as well as a comprehensive health and hospital
 information system (GNUHealth).
 .
 The purchase secondary unit module adds a secondary unit of measure on purchase
 lines.
 The secondary quantity and unit price are kept synchronized with the quantity
 and unit price.
 The secondary unit is defined on the product supplier or on the product with
 its factor against the purchase unit.