Reg,
Agreed; your conclusions all looks pretty reasonable to me! What about Warsaw pact countries that the Soviets used to for their second string aircraft and then gave them their designations, maybe competitor project of the Delfin and Iskra?
More or less ground to a halt now and in serious need of further info!!
I expect you'll be turning in soon, sleep well mate, I'm pretty sure it'll still be here in the morning (unless the Wizard has it in one of his books)!!
Edited to say;
Aha!! I see that WK's light has just come on, so dont go yet mate!!