HDC Handbook

Board, Layers & Notation

Last updated: June 1, 2026

In HDC every position is described in three-dimensional space. To keep orientation manageable, the game uses a clear coordinate system.

This page explains the playing space, the layers, the key square names, and the basic idea of notation.

The playing space

HDC is played on a fixed 3D grid:

8 files: A to H
8 ranks: 1 to 8
8 layers: I to VIII

Together that makes 512 squares.

How to read a square

A square is written with three parts:

file
rank
layer

Examples:

E1–IV
A8–I
C5–VI

This is practical because a square in HDC is no longer located only on a board. It also has a height in space.

The axes in simple terms

X-axis

These are files A to H.

Y-axis

These are ranks 1 to 8.

Z-axis

These are layers I to VIII.

The reference layer IV

A special role is played by layer IV. It is the most important reference layer and in many situations feels like the classical board at the center of the cube.

That is why layer IV appears so often in examples.

Orientation from White’s side

The orientation is fixed:

A1–I is front-left-bottom
H8–VIII is back-right-top

The coordinate system does not rotate with the player.

Color parity in space

Square color still matters in 3D, especially for bishops and knights. The square color follows from file, rank, and layer together. For regular players, the important practical points are:

bishops remain color-bound
knights change square color with every move
pawns behave differently depending on how they move

You do not need to calculate this during normal play, but it helps to know that the color structure inside the cube is systematic.

Why notation matters in HDC

With the added layer dimension, precise square names are even more useful than in classical chess.

Notation helps you:

read examples clearly
understand special rules
record moves unambiguously
share or save positions

Short notation examples

e4–IV for a pawn move
Df4–VI for a Duke move in English notation
O-O for short horizontal castling
O-Oz for lower Z-castling
e5–Vxe6–IV e.p. for an en passant example with a layer change

Canonical piece letters

HDC uses the same piece letters in English and German pages. Piece names may be localized; notation letters stay canonical English.

King = K
Queen = Q
Duke = D
Rook = R
Bishop = B
Knight = N

HDC-FEN and saved positions

HDC uses its own position format called HDC-FEN. This format can describe all layer contents, the side to move, castling rights, en passant targets, and further state data.

For players, this becomes especially useful once example files are available to download.

Coordinates in the image

The diagram shows how file, rank, and layer define one square together. A square is not just on a board; it has one exact position inside the cube.

HDC coordinate system with X file, Y rank, Z layer, and a marked example square — X is the file A–H, Y is the rank 1–8, and Z is the layer I–VIII. A square such as E4–VI combines all three parts.

FileView as a file slice

A FileView slice fixes one file, for example E, and shows the relationship between ranks and layers. This is especially useful for reading vertical structures such as the noble column.

FileView slice through the HDC cube with one fixed file and multiple layers — FileView means: one file stays fixed while ranks and layers become visible.