Travel details and itinerary for subsequent trips of a 2yr tourist L type for UK citizen.

I'm planning a backpacking trip that will require multiple entries to China in the course of a year, do I need to provide details for each of these entries in order to get a 2 year multiple entry Visa, I don't know the exact date or accommodation details for my first entry at present if these change in the future will it mean the visa is no longer valid?