Well, it's natural to stratify all chess positions by pawn structures. I started to look at Game Explorer (up to A50 now) and to make a list of principal strata. I'm also planning to describe all transitions between them.

• 3b|5d          Nimzo-Larsen: classical                   1.b3 d5
• 3b|5e          Nimzo-Larsen: modern                     1.b3 e5
• 3b4c|5d6c  Anglo-Slav: Bogolyubov                   1.Nf3 d5 2.c4 c6 3.b3
• 4b|5e         Orangutan / Polish / Sokolsky           1.b4 e5
• 4c|5c          Symmetrical English                          1.c4 c5
• 4c3g|5c6g  Symmetrical English: fianchetto     1.c4 c5 2.g3 g6
• 4c|5d          Réti                                                      1.Nf3 d5 2.c4
• 4c|5e          King's English / reversed Sicilian      1.c4 e5
• 4c|5d6c      Anglo-Slav                                         1.Nf3 d5 2.c4 c6
• 4c|5f           Anglo-Dutch                                       1.c4 f5
• 4cd|6d        Old Indian                                           1.d4 d6 2.c4
• 4cd|6g        King's Indian                                      1.d4 Nf6 2.c4 g6   
• 4cd|6dg      Modern defense                                1.d4 g6 2.c4 Bg7 3.Nc3 d6
• 4ce|6e        Anglo-Indian: Flohr-Mikenas-Carls   1.c4 Nf6 2.Nc3 e6 3.e4
• 4c3g|5d6e  English: Agincourt                             1.c4 e6 3.Nf3 d5 3.g3
• 4c3g|5e6g  Anglo-Indian: fianchetto                    1.c4 e5 2.Nc3 Nf6 3.g3 g6
• 4d|5c         Old Benoni                                         1.d4 c5
• 4de|5c6g   Pterodactyl                                         1.d4 g6 2.e4 Bg7 3.Nc3 c5 
• 4f|5d          Bird: reversed Dutch                          1.f4 d5
• 3g|5d         King's Indian attack                            1.Nf3 d5 2.g3
• 4g|5d         Grob                                                   1.g4 d5

... to be coninued

Hey Bojan, it might be a cool project!

Many transitions are obvious just from their stratification codes. For example,

3g|5d + 4c|6e --> 4c3g|5d6e

indicates how someone can transit from King's Indian attack (A07) to English: Agincourt (A13).

LoL  Actually, not so much hard work, everything is almost obvious!

Ajedrecito, nice! U can write 3c4de|5cd6e instead of 3c4d4e|5c5d6e. And yes, the push of white e-pawn is +1e|.

Yes, indeed, U have nicely explained the basis of my presentation.

Very nice example for a transposition bolevole - I was not aware of that !

There is another example, that I like:

Do you know more of them ?

Cheers, Winnie

Cool !

Transpositions are amazing tools. Luring opponents into your own system !

Winnie, nice example of Anglo-Slav --> Caro-Kann: Panov attack transition!

terrible, white has not advanced 5e4e and black already has 5c