PowderCell uses the key-word spgr as code for the beginning of a space-group record . It follows the number of space-group type (227) and the setting (1.) The third number (15) represents the Laue group, which is important if the anomaleous dispersion is deactivated. The 0 represents a flag symbolizing the absence of an inversion centre in the origin (but there exists an inversion centre, as you can see from the last generator described by type1). Using the listed generators 48 general positions will be created. Besides the position of general symmetry 8 special positions exist. To generate all 48 different symmetry elements 5 generators are given and must be feeded into the program. At the end of the first line of the record the full Hermann-Mauguin symbol (F 4_1/d -3 2/m) will be presented.

In the second line the reflection conditions will be given in dependence on the defined reflection type. So e.g. the intensity of 00L will be calculated only than, if the condition 19 (i.e. L=4n) will be meeted. For the reflection type 0K0 the condition 17 is determined. This corresponds to the condition K=4n.

The third line contains all information about the existing Wyckoff positions: the type and the generator sequence. The types don't shall be described here in detail. However, the encoding of the generator sequences shall be represented in a short manner.

For each Wyckoff position two values will be presented in the record. The second of this describes the generator sequence. In the line you will find the same order of special positions as listed in IT. The order starts with that position describing by the Wyckoff letter a but doesn't consider the general position, i.e. if no special position exists no value is given in this line of the record. In our example some of the 8 Wyckoff-position types will be described by the same generator sequence, e.g. for a and b will be used code 16 or c and d are described by code 6. That means that both positions will be characterized by the identical local symmetry. However, the Wyckoff positions e, f, g, h will be generated by a different generator sequence — 22, 26, 30, 46. The encoding is very simple using a bit structure. In our example the generator type 1 will be presented by bit 0, type 5 by bit 1, type 13 by bit 2, type 3 by bit 3 and type 4 by bit 4. In dependence of the generator sequence the bits are activated or not. If within the unit cell only one symmetry-equivalent position exits, no generator must be used and therefore no bit is activated. The result is code 1.