It is in the user guide for the 3.02.17f user guide, in that it specified the data type.
Like az1324 said, RAM1, RAM1H, RAM1L, RAM10, RAM11, RAM12, RAM13, and RAM1B0..RAM1B31 are all reference to same RAM location. It just provides you a way to access them in 32bit, 16bit, 8 bit, or one bit.
The bit access is only available for RAM1.