OK, well, answering my own question here, but I did a little more digging and found that "operational" is synonymous with "due Regard" in the ATC sense. The term appears to be from the US in origins.
The FAA Pilot/Controller Glossary and
]FAA JO Order 7110.65W show the two terms to have the same meaning.
Just thought I'd throw that out there in case anyone else was scratching their head about this.