I have not checked this idea fully. So, do this at your own risk.
Create a new family for a parking space from the Generic family template. Assign this generic family a specific category like door, window or casework in the Settings > Family category and parameters.
Use this family to create your parking layout.
Then you can tag these families (using the door tag or you could create a separate tag to show the mark value). You have to be careful to appropriately exclude these families if you schedule these items.
HTH
nicholas iyadurai
www.nichitecture.com