Lars:
Accurate deduction. P is Sven Palmqvist and 4192 is the production number, one sequence for entire company, designed in early to mid 60's, and 111 is the number assigned to this variant, either different size or slightly modified design.
There is not a very complete online resource for Orrefors signatures. Bill Geary, an author and Scandinavian glass expert, in another thread recommended "Orrefors, A Century of Swedish Glassmaking, "Editor: Kerstin Wickman, Publisher: Byggförlaget-Kultur ISBN: 91-7988-152-1. The last chapter in that book by Ulrika Ruding is the most complete account I've seen. It still doesn't explain all Orrefors signatures, at least for me, but that may be my problem. It's an expensive book, though. For production Orrefors pieces designed before 1961 (not graal, ariel, expo, etc) the best work is "Swedish Glass Factories, 1915-60," which reprints many catalogues, by Helmut Ricke and published by Prestel. The book is out of print and can be insanely expensive, but it's worth it if you're collecting 1930's-1950's Orrefors or Kosta pieces. I kept looking until I got it for around 100 euros if I remember.
David