Binary operations

GSL supports combining multiple queries using logical operators to refine selections further.

Logical AND

Operators: and or &&
Function: Selects atoms that satisfy both queries.
Examples:
```
name P and resname POPE
```
Selects atoms named P in residues named POPE.
```
serial 256 to 271 && resid 17 18
```
Selects atoms with serial numbers between 256 and 271 in residues 17 or 18.

Logical OR

Operators: or or ||
Function: Selects atoms that satisfy at least one of the queries. Can be understood as an addition (+) operation.
Examples:
```
name P or resname POPE
```
Selects atoms named P + atoms in residues POPE.
```
resid 17 18 || serial 256 to 271
```
Selects atoms in residues 17 or 18 + atoms with serial numbers between 256 and 271.

Operator precedence

When combining multiple and and or operators, GSL evaluates them from left to right.

Example:
```
resname POPE or name CA and not Protein
```
Interpreted as:
(resname POPE or name CA) and not Protein

Selects atoms in residues named POPE + atoms named CA − (minus) atoms that are part of the "Protein" group.

Combining with autodetection macros

You can mix autodetection macros with other queries using logical operators.

Example:
```
@membrane or group 'My Lipids'
```
Selects all autodetected membrane lipids + atoms in the "My Lipids" group.