Transpositions: one position, several move orders
Openings are named after positions, and positions can be reached in more than one way.
A transposition is a different order of moves that reaches the same position. The list behind this site contains 393 lines that pass through a named position by a move order other than that position’s own, and 308 names are attached to two or more lines, each a separate route to the same named position.
Positions, not move orders
Openings are named after positions. 1.d4 Nf6 2.c4 e6 and 1.c4 e6 2.d4 Nf6 lead to the same board, so they carry the same name. The list handles this in two ways. Sometimes it gives one name several entries, one per common move order. Sometimes it names only one order, and other lines simply pass through that position on their way somewhere else. This site compares positions, not move sequences, so both cases are found.
Names with several routes
These names have the most separate entries in the list:
| Name | Entries |
|---|---|
| Italian Game: Classical Variation, Giuoco Pianissimo | 17 |
| Queen’s Indian Defense, with e3 | 14 |
| Bogo-Indian Defense: Retreat Variation | 12 |
| French Defense: Winawer Variation, Positional Variation | 12 |
| Nimzo-Indian Defense: St. Petersburg Variation | 12 |
| Queen’s Pawn Game: Torre Attack | 11 |
| Sicilian Defense: Closed | 11 |
| Catalan Opening: Closed | 10 |
Italian Game: Classical Variation, Giuoco Pianissimo leads with 17 entries. Every entry is a full move sequence of its own, and each code page lists them in its table of lines, so the different routes can be compared move by move.
Which openings transpose most
Counted by opening name, the lines that pass a named position by another order belong mostly to Queen’s Gambit (101), English Opening (34), Sicilian Defense (32), Italian Game (29), Semi-Slav Defense (25). Measured against their size, the picture changes: Catalan Opening (44% of 32 lines), Queen’s Gambit (37% of 275 lines), Semi-Slav Defense (34% of 73 lines) have the highest shares among openings with at least thirty lines.
How far transpositions travel
We counted every point where a line passes a named position by a different order. Of those 833 crossings, 297 stay within the line’s own code, 502 cross into another code of the same volume and 34 cross into a different volume. The commonest bridge between volumes runs from D to E: 19 times a line filed in D passes a position named in E. Next comes D to A (7).
- Within the same code297
- Into another code, same volume502
- Into a different volume34
One name, several codes
A name with several routes does not always stay in one code. One hundred and eight names in the list have entries under two or more codes. Nimzo-Indian Defense: Sämisch Variation is spread furthest, over 6 codes (E24, E25, E26, E27, E28, E29); Dutch Defense: Classical Variation appears under 5 (A84, A90, A91, A92, A96). Each of those codes holds its own entry with its own move order, and each code page shows that route on its score sheet.
When transpositions happen
Transposed lines are longer than average: their median length is 14 plies, against 9 for the whole list. The earliest point at which a line meets a named position by another order is ply 3, which happens in 16 lines; the middle half of all first crossings falls between plies 6 and 11. By volume, D has the highest share of transposed lines, 25% of its 644, against 6% in C.
An example: the Najdorf by another road
The Najdorf, B90, is defined by 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6. But a line filed under B92, Sicilian Defense: Najdorf Variation, Opocensky Variation, reaches the same position after 1.e4 c5 2.Nf3 Nf6 3.Nc3 d6 4.d4 cxd4 5.Nxd4 a6: Black plays 2...Nf6 before ...d6. The finder, and the code pages, recognise the Najdorf in both cases.
Codes with most transposed lines
The codes whose lines most often pass a named position by another order are C56 (15), D63 (10), D79 (10), D45 (9), B06 (8), C19 (8). In total 85 codes have at least one named position that another code’s line reaches by a different route; each of their pages has a section called “Other move orders” listing them.
What this means for your games
If you reach a known position by an unusual order, the name still applies: the position is what counts. That is also why you should not stop reading a game at the first unfamiliar move order. Enter the full sequence in the opening finder; it checks every position along the way against all 3,865 named positions in the list. Because it compares whole positions, including whose turn it is and the castling rights, two boards that look alike but differ in those details are kept apart.
Sources
Opening names and move sequences: lichess-org/chess-openings (CC0), retrieved 2026-10-28. All counts replayed and computed by ecocodes with python-chess; definitions on How to read a code page.