ID:13752 VHDL Subtype or Type Declaration warning at <location>: subtype or type has null range

CAUSE: In a Subtype Declaration or Type Declaration at the specified location in a VHDL Design File (.vhd), you declared a range for a subtype or type. However, you either specified an ascending range and specified a left bound for the range that is larger than the range's right bound, or you specified a descending range and specified a right bound for the range that is larger than the range's left bound. As a result, the range is empty, or null.

ACTION: To avoid receiving this message in the future, or if you do not want the range to be null, switch the left and right bounds of the range so that an ascending range has a right bound that is larger than the left bound, or so that a descending range has a left bound that is larger than the right bound. Otherwise, no action is required.