What constitutes the specified location (mahall) for a salam contract?
Chapter on Guaranteed Salaf (Advance Payment) for a Specified Term
Al-Mughni
Book of Sales
Primary text
The specified location is what the contracting parties designate as the place of delivery. In cases where the subject matter is not yet in existence but is agreed upon for a future time, the place is that which the parties choose.
Supporting text
It is argued that if the item's existence at the contract time were required, it would follow that the delivery periods for salam would become unknown, yet the parties have not designated a location in the context where this objection is raised (implying that the lack of current existence does not invalidate the choice of future location).