ID:13855 VHDL Subprogram Declaration error at <location>: object class for formal parameter of function cannot be <name>

CAUSE: In a Subprogram Declaration at the specified location in a VHDL Design File (.vhd), you used the specified object class for a formal parameter of a function. However, the formal parameter must have an object class of CONSTANT, SIGNAL, or FILE.

ACTION: Change the mode of the formal parameter to CONSTANT, SIGNAL, or FILE.