Store PO Details

We have several clients who will raise an annual PO with us for services and then call off services and use the same PO each month until it's used up.

What I'd love to be able to do is store client PO's on the system.

PO Table would be something like:

PO Number, Total Value, One-Off/Call Off, {if prior field is set to call off} include valid from date and valid to date (allow null valid to), Add a narrative field.

When creating a client invoice, the reference field would carry out an in-line search and have a "find" button which lists all POs for the current client that a) have money available on them, b) are within the date range. Selecting this PO would effectively act in a similar way to my little credit limit feature you implemented a few years ago where it carries out a parity check and warns the user if the invoice value goes over the amount remaining on the purchase order.

We currently store these in a separate system ("notes" field on our CRM), and I think this could be a more elegant way of linking POs to clients. It also reduced the risk of typos/incorrect copy&paste delaying payments.

For a deeper integration in to the system, looking at the PO history would allow a one-touch list of invoices raised using each PO number.