They move the Quantity Needed into the location's on-hand stock, to be used once the meals have physically arrived at the location:

• Update Stock (top button) processes every line on the day's menu; the per-line Update Stock button processes one meal/portion only. Both ask Are you sure you want to update stock? first.
• For each line, Sprwt adds the Quantity Needed to the location's stock as an Add movement. In the current version this movement is recorded under the reason code labelled Checkout, not Sold - it is a different reason than the one a stock-upload's Deduct as Sold option uses.
• Running the top Update Stock button again for the same date only adds the difference between the new Quantity Needed and what was processed before, so raising a quantity from 10 to 15 adds 5 more, not 15. Lines with Quantity Needed 0 are skipped.
• After processing, Quantity in Stock and Last Stock Update in the table refresh, and any stock alert thresholds are re-checked.

In the current version, using the per-line button on one portion of a meal also marks every other portion of that same meal as already fully processed for that day, without actually adding their stock. If a meal has more than one portion size, use the top Update Stock button (which processes every portion correctly) rather than the per-line button, to avoid a portion silently missing its stock addition.