May I please recommend allowing Custom Scenarios to use Instruction Screen Maps?

In the AOE: DE Scenario Editor in the “Cinematics” menu, there is a box where you can pick a map to go with your Instruction Screen. Certainly, there must be formatting requirements for the map to work (eg. size, file type, BMP vs. PNG, etc.). Are there instructions for map requirements available? For example, AOE1 (original version) came with a “Default” .BMP map file that you could easily draw on and use to make AOE1 Instruction Screen maps. I heard that you cannot use this feature if you are a Custom Scenario designer, however.