Conceptually, PyMOL atom selections are simply lists of atoms. These lists are used as input to many commands, as selection expression arguments
If you wish to use a selection expression more than once, then you can use the select command to associate it with a unique name that can be used repeatedly in other selection expressions.
An alphabetical list of selection operators is available along with a list of those that are deprecated.
Selection macros provide a quickhand way of specifying atoms without having to provide explicit operators.
b | q | partial_charge | formal_charge | ss | hetatm | bonded | enabled | present | state | visible | color | cartoon_color | ribbon_color | flag | numeric_type | text_type | User-Defined Properties (New in 1.6.1)
byresidue | bychain | bysegment | byobject | bycalpha | byfragment | bymolecule