Sivakumar covers Calculating Quantity on Hand in Inventory in his newest post.
Apologies to Siva, I originally listed this as Vaidy’s post. There are so many great GP posts coming out that I’m struggling to keep up.
Calculating Quantity on Hand in Inventory | Interesting Findings & Knowledge Sharing
Archived post from 2011. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.