# Selection rules

Most commands of the CYANA command groups atoms, angles, distances, peaks, shifts, angles, couplings, rdc, pcs, and structures apply to sets of these objects.

The following objects can be selected in CYANA:

- Atom selection
- Angle selection
- Peak selection
- Distance restraint selection
- Scalar coupling selection
- Residual dipolar coupling selection
- Pseudocontact shift selection
- Structure selection

Atoms or torsion angles are the basic units of selection. Peaks, distance restraints, and scalar couplings are selected as pairs of atoms, possibly subject to additional conditions. Chemical shifts are selected by the corresponding atom. Torsion angles can be selected in the same way as atoms, using angle names instead of atom names.

Selections can either be volatile, i.e. be used temporarily for the current command, or persistent, i.e. be used for the following commands. Persistent selections are made with the commands **atoms select**, **angles select**, **distances select**, **peaks select**, **couplings select**, **rdc select**, **pcs select**, and **structures select**. Selections made by other commands are always volatile.

Ranges of numbers in selections, e.g. residue ranges, can be specified in one of the following ways:

*m*- A number
*m*..*n*- A range of numbers
*m*-*n*- Alternative format for a range of numbers (only for
*n*≥ 0) *m*..- From number
*m*onwards *m*-- From number
*m*onwards; alternative format - ..
*n* - From the first up to number
*n*.