Purchase orders And stock adjustment

suggestions as follow:

1.enable free text to enter supplier’ reference number to the PO

2.allow input in amount in “- stock” like “+stock” does (sometimes there would be need for specific the stock price instead of deducting by the average stock cost)

3. Enable an adjustment function in PO basis (it would be helpful when we get a discount, say 5% for the PO in a particular month, in a monthly settlement with the supplier for few PO that have been received and record in the stock balance in earlier time)