BPM when inventory is consumed - how to determine when inventory was consumed?

We have to account for customer owned inventory(we have a user defined field on the part table to tell us what parts are customer owned), and we have processes that seem to be working pretty well… One feature that was requested is we want to send an automated email when customer owned inventory gets consumed. In part tracker I believe you can see this via a green checkbox on the material, but I’m unsure what field in the database this coincides with. That is I think we can simply trigger on this “consumed” if the given part is customer owned inventory to know to send the email.

Are we on the right track? If so what is the field that tells us if a given inventory on a job was consumed?

One more thought, above is thinking in terms of database fields(data directive) but I think a method directive might be easier to implement… Is there a inventoryQtyAdjust() type method we could attach a bpm to?

@embedded do you consider it consumed when it is issued to the job then a DD on Jobmtl where the Part has the check or you have a UD on JobMtl. I do a lot of alerts like this.

Or, Is it consumed when that job is finished or shipped or closed?