HAL4RT — Difference between HAL_NULL_PARAMETER and HAL_BAD_PARAMETER is ambiguous

In the section 7.3, some return codes are defined.

The meaning of HAL_NULL_PARAMETER is described as "The parameter is not supported." The meaning of HAL_BAD_PARAMETER is described as "The operation failed because an illegal argument was passed to it."

The difference between "unsupported parameter" and "illegal arguments" are ambiguous, and usage of return codes are not defined clearly in the following specification description. This definition might confuse implementors.