# Direction Create

- Type
- Projection
- Line
- View

### reference

When reference is cell, the direction is crystallographic, its parent must be a cell and the direction indices must be indicated. When reference is atoms, the direction is atomic and must contain two non coincident atoms defining a line.

    Example: <direction ... reference="cell"/> (default)
    Allowed values: cell, atoms (optional)

### u, v, w

Set the indices u, v, w defining a crystallographic direction. The three indices cannot be all zero. An error is shown when these indices are not indicated for a crystallographic direction or when they are indicated for an atomic direction.

    Example: <direction ... u="1" v="0" w="0"/> (no default)
    Allowed values: integer (required, coupled)

### vectors

Set the type of cell vectors, conventional or primitive, used to determine the direction with u, v, w indices. When the lattice is primitive there is no difference between conventional or primitive cell vectors. An error is shown when vectors is set for an atomic direction.

    Example: <direction ... vectors="conventional"/> (default)
    (defined in GAMGI_PHYS_DIRECTION_VECTORS)
    Allowed values: conventional, primitive (optional)

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