(d) Starting and stopping (piston engine).
(1) The design of the installation must be such that risk of fire or mechanical damage to the engine or airplane, as a result of starting the engine in any conditions in which starting is to be permitted, is reduced to a minimum. Any techniques and associated limitations for engine starting must be established and included in the Airplane Flight Manual, approved manual material, or applicable operating placards. Means must be provided for--
(i) Restarting any engine of a multiengine airplane in flight
My understanding is that the maximum altitude at which an engine can be started may be below the maximum operating altitude, provided it's documented in the AFM.