See here. The UDATA directive declares a chunk of uninitialized data-- i.e., all or part of the PIC's data registers. The RES directive means "reserve" and is used to declare user variables and their size.He says UDATA and RES are directives.
Where are the definitions for those?
In a single assembly file program, equ is commonly used to assign a variable name to an address location in RAM. Do not use this method for assigning variables when building a linked project; use a res directive inside a data section directive (idata, udata).