To keep Herschel running quickly it's important to periodically maintain your works order data.  

 

The delete old orders option deletes completed works orders which were entered before a given date.  Uncosted orders can be omitted, as can orders which have not been completely kitted:



As well as deleting old orders, this option also tidies up the kit lines associated with each order, and corrects the stock figures of any unissued components.