Cell names were not part of the original CIF syntax specification. Various extensions have been used to supply cell names in a CIF file. Each of these extensions consists of command following the ``DS ...;'' command, in the following forms:
| cname_index | Historic Name | Format |
|---|---|---|
| 0 | IGS | 9 cell_name; |
| 1 | Stanford/NCA | (cell_name); |
| 2 | Icarus | (9 cell_name); |
| 3 | Sif | (Name: cell_name); |
| 4 | none | no extension used |
In Xic, any of the first four forms (indices 0-3) will be recognized equivalently when reading CIF input.