When to use it. The stock exists, but in the wrong place: the branch across town is out of what the main store is holding. A transfer moves quantities between two of your own warehouses in one document — out of the source, into the destination, at the same moving-average cost, so value travels with the goods and the company's total stock value does not twitch.
How it runs. Draft the transfer (§5.7) with a line per product: from-warehouse, to-warehouse, quantity with its unit. On posting, both sides move in the same act — there is no half-moved state for stock to get lost in. For a lot-tracked product the transfer carries the same lots to the destination, chosen in the same FEFO order an issue would use: the batch that left is the batch that arrives, dates and all, so a lot's story (see Lot Trace, §5.10) reads straight through the move.