### type

Controls the representation of the cell lattice, which can be:
1)

**conventional** (the lattice is constructed using

**n1**,

**n2**,

**n3** conventional cells; 2)

**primitive** (the lattice
is constructed using

**n1**,

**n2**,

**n3** primitive cells);
3)

**wigner** (the lattice is constructed using

**n1**,

**n2**,

**n3** Wigner-Seitz cells); 4)

**parallelepiped** (the lattice is filtered
by a generic parallelepiped volume, with length parameters

**v1**,

**v2**,

**v3** and angle parameters

**v12**,

**v13**,

**v23**);
5)

**sphere** (the lattice is filtered by a sphere with radius

**v1**);
6)

**projection** (the lattice is represented by its stereographic projection).

Example: **<cell ... type="conventional"/>** (default)
Allowed values: **conventional**, **primitive**
**wigner**, **parallelepiped**, **sphere**,
**projection** (optional)

### n1, n2, n3

Control the number of lattice cells created along
the directions defined by the vectors

**a**,

**b**,

**c**,
when

**type** is

**conventional**,

**primitive**
or

**wigner**. Indicating some or all of these parameters when
the cell type does not require them is flagged as an error.

Example: **<cell ... n1="1" n2="2" n3="3"/>** (default)
Allowed values: positive integer (optional, coupled)

### v1, v2, v3, v12, v13, v23

When

**type** is

**parallelepiped**, these six parameters are needed
to indicate the edge lengths and angles of the filtering parallelepiped.
Each angle must be smaller than the sum of the other two and must be larger
than the absolute difference of the other two, otherwise an error is produced.

When **type** is **sphere**, the **v1** parameter is needed to
indicate the radius of the filtering sphere. Setting parameters that are
not required for a given cell type is flagged as an error.

Example: **<cell ... v1="5.0" v2="6.0" v3="7.0"
v12="60.0" v13="70.0" v23="80.0"/>** (no default)
Allowed values: positive real (required)