I hope I'm not missing something simple, but I'm trying to stop the user before they move off of the Header tab of Sales Order Entry if the warehouse is equal to X, so that I can force them to change to a valid warehouse code prior to them getting to the Lines tab. It's important that all new lines adopt the correct warehouse code. Is there a way to ""require"" a field when they try to focus on a new tab? Or maybe I'm thinking of this the wrong way - maybe there's a more efficient or cleaner way to go at this?