NavList:

I like your conjectures, Alex. I was going to suggest it's just a "brand name", but given soviet era socialism, probably not! I have a related guess though... 

Acronymic names like this are often assigned to projects deep within bureaucratic organizations when they are launched, and they reflect the intentions of the project at the outset. But when they're done, the project has travelled in an entirely different direction while retaining the original project title. It's a sort of a bait-and-switch. Did the Soviet Navy need a "tropicalized" sextant in 1955 (or whenever the project was launched)? On paper, yes, and paper is what counts to get funding within the bureaucracy. I can imagine the "sales pitch" speaking of the future needs of a soon-to-be global navy of the USSR... Once you have funding in place, you build, or borrow, whatever makes sense based on real practical needs. Deliver it under the "tropicalized" project, slap a label on it, and you've actually succeeded in producing a great sextant within the confines of a system that doesn't "know" what it needs in advance.

My "theory" here will probably remain little more than a suggestion until the records of the design teams on these projects are made available to professional historians. I suspect, though, that those records are classified as state secrets.

-FER