Packet Size - 13 words
| SEQ | Description |
| +1...+9 | Rotation matrix to relate Miller indices of a reflection tothose of its twin-related reflection. |
| r11, r12, r13, r21, r22, r23, r31, r32, r33 | |
| h' = (r11 r12 r12) h | |
| k' = (r21 r21 r23) k | |
| l' = (r31 r32 r32) l | |
| Note that if the space group is non-centrosymmetric,each packet corresponds to two twin laws, i.e. the givenmatrix multiplied by +1 and by -1. | |
| +10 | twin volume ratio |
| +11 | esd of twin volume ratio |
| +12 | volume ratio of the inverse (if non-centrosymmetric) |
| +13 | esd of volume ratio (if non-centrosymmetric) |