Not possible to create standalone invoice lines
Creating a new invoice_line is not possible, every field is read-only.
(further readings: http://www.tryton.org/~irclog/2017-01-31.log.html#t2017-01-31%2009:52)
Creating a new invoice_line is not possible, every field is read-only.
(further readings: http://www.tryton.org/~irclog/2017-01-31.log.html#t2017-01-31%2009:52)