It can be done, but I suggest you rethink your table design. If I understand you correctly, you have multiple fields in each record in your order table for listing the individual items sold on that invoice. I suggest you create a related table of line items and use a portal to that field for listing the items purchased in that order.
This is both more flexible--there's no longer any limit to the number of items you can purchase in a single order, but it's also much simpler to work with to get your calculations--which appear to be the unit price of a specified item times the quantity.
Thanks for your quick response. I have not used Filemaker for this type of thing before. I have one table "catalogue" that contains approximately 2000 records containing information that has been recorded and stored in an archive. I have a second table that I have just set up for ordering these audio or video files in various formats. I already have a portal to the "order table" from the "catalogue" that brings up the specific record in the order table by a date and time relationship. Do you suggest I create a third table? and if this is what you think, how would you lay that out?
Thanks for your input!
Thanks for your help. I believe I have it figured out.