PLSN/PLASN isn't my invention - I saw it elsewhere, and directly I took it from Apalkov (and I think we both agree that he rather knows about these things more than two of us combined). Also, as for the "using it for other designations", I think that it would be acceptable, since VMF had a number of very peculiar (full-sized) submarines (either purpose-built or conversions) that had/have equally peculiar, often one-off and highly obscure hull codes (like Pr.640 radar picket subs based on Pr.613; Pr.690 target subs, numerous weapons trials vessels etc.) which would be difficult to follow and I'm not sure if they would be any less confusing for anyone outside people professionaly related to the Soviet/Russian submarine force.
Also, despite that footnote from one of Apalkov's books I quoted above, it (PLSN/PLASN) seems that it's in quite widespread (and, I suppose: formal) use for various specialized vessels - other Apalkov's book, the Korabli VMF. Tom 3 chast 2, Protivolodochnye Korabli. Malye Protivolodochnye Korabli
in the extended part devoted to annexes to the earlier parts of the series, includes the Pr.690 Kefal (NATO: Bravo) target submarine (pages 83-84) described there under code PLBSN(ts) Pr.690, while the list of acronyms on the page 105 gives such codes as PLBSN and PLMSN, which are variants of PLSN, just with B and M for Bolshaya (large) and Malaya (small) respectively. the (ts) seems to me to denote short for (tsel) - target. Also, the text of the series (although I have to admit I didn't had time yet to study it in depth) suggest other such shorthands in ( ) for other specialized variations. That said, however, I believe that using the Bolshaya/Malaya and (...) elements would be excessive, while the basic PLSN/PLASN seems to me a legit code.
Indeed, the PLASN fits perfect for the Delta IV-based carrier. But I think that it would fit for the Losharik as well, since it's actual purpose
it's actually quite obscure, but certainly is rather special
On a note: I think that proper designation for this Delta-conversion is Project 09787 - at least according to Russian-Ships:
http://russianships.info/eng/submarines ... 67bdrm.htm
As for the internal structure - not exactly Pr.667BDRM, but Pr.667BDR (Delta III), but I hope it would help anyway:
Btw. don't be confused by the APKR code - it's just an alternative type of designation: Atomnyi Podvodnyi Kreysier, Raketnyi - Nuclear Submarine Cruiser, Missile-armed.
P.S. The code chart has been updated.