When to Use Detailed Descriptions

If you are creating a new design targeting a Xilinx CPLD, you need only use pin-to-pin descriptions. You are free
to use any of the additional supported dot-extensions (such as .CE, .LH and .T) if it allows you to more
conveniently express your design behavior.

If you are reusing an existing ABEL module that was originally targeted for a different PLD architecture, your
design may contain detailed architecture-specific descriptions. Any of the supported descriptions (such as the
istype'invert' attribute or the .Q feedback extension) will be correctly emulated by the Xilinx CPLD fitter to
maintain the original logical behavior.