This may arguably be a two-fold question, but as far as I understand it, the whole coding system that WOTC adopted for the 4th edition is intrinsically connected with the worlds that were created throughout the campaign books.
One thing that I couldn't quite manage to define was the listing as well as the division of all the worlds that are contained in the 4th Edition books.
Only a few of them have I managed to enlist, such as:
- Dark Sun
- Forgotten Realms
I feel that there are many other worlds and this whole coding system is a way of separating the campaign and tools' books accordingly.
For instance "Orcs of Stonefang Pass" is a HS2 book, which I completely fail to understand what that HS2 means, as well as which world does that campaign belong to.
Some other examples are:
- Keep on the Shadowfell H1
- King of Trollhaunt P1
- Demons Queen's Enclave P2
- Assault on Nightwyrm Fortress P3
I can clearly see a pattern there for the previous 3 books, P1, P2 and P3, being each previous book a prequel campaign for the following one. Still, the P code is a mystery to me.
I could place a world to the for campaigns listed above, being all of them situated into the Shadowfell world, as well as "Death's Reach E1", which is an E1.
Well. I guess you get the picture. If you could help me out listing the worlds as well as getting the hang of these codes' meanings, I think it would be a great source for latter apprentices, just like me.