I assume from your comment that you are in a make to stock environment.  So when a S/O is taken you should already have the inventory there?  So this also means that you try to satisfy orders on the date the order is taken?  So based on how you measure there are numerous ways you could get the data.  For example look at Sales Order Tracking Inquiry.  You see the results from a shipment as an invoice and there you can see the qty ordered, qty shipped.  You can also see the different dates, e.g order date, due date, ship date etc.

QAD holds history in a lot of detail.  So for example you could create a browse based on tr_hist for transaction type "ISS-SO" and pull data from there in a browse.

Since you are new to QAD, I would advice you to get an online training on the Metrics tool (hyperlink)..

There are many courses start with the overview to get an idea of what you can expect.

Regarding your question, depending on "when" you want to know something data is stored in a different table/file.

For example: is the file rate based on what you "want to ship" or what you "have shipped"?

Or is the fill rate also based on "due date"? If you want 100 pieces on the 20th of the month (due date) and today is the 10th. Is there a fill rate calculation and what is it?

If you have defined all these questions it is advisable to hire a consultant who can help you (initially) find the data files.

After this first start you can find more help in the QAD manuals. (database definitions / file relations)

NOTE: In 2016 there are many standard metrics available. type "metrics" in the menu bar.