Normally, there are no restrictions or limitations on the name of a booking.
Do note that these names are re-used as a service name when creating a service booking.
However, if you are using Elastic indexing database to store your data and you want to play it safe, then I would recommend to be consistent with the naming conventions for the SRM properties. Why? Because SRM property names are indexed in the database.
I currently do not know any limitation or restriction of other databases.
Please do see our documentation for more information: Allowed property names
Hope this will help you further.