negative modifiers

Like many other product - Linga needs to allow negative Modifiers.

Its not difficult to do and should only need a change to the DB to allow negative values. As it only adds a modifier line to the order it should not affect the tax calculation

Having reviewed some 50 systems I can honestly say its in most other system and is urgently needed in Linga. Without this it creates a nightmare for us to use the system.

Linga is a great product but could be so much more by allowing negative modifiers