Parentheses

Parentheses allow you to control the evaluation order of your queries.

Changing evaluation order

Use parentheses to group queries and dictate the sequence of operations.

Example:
```
resname POPE or (name CA and not resid 18 to 21)
```
Selects atoms in residues named POPE + atoms named CA which are not in residues 18 to 21.
Changing the position of parentheses:
```
(name CA or resname POPE) and not resid 18 to 21
```
Selects atoms which are either named CA or in residues named POPE, but are not in residues 18 to 21.

Nested Parentheses

You can nest parentheses to create complex selection logic.

Example:

serial 1 to 6 or (name CA and resname POPE || (resid 1 to 7 or serial 123 to 128)) and Protein

A valid, albeit complex, query that combines multiple conditions.

Negating Parenthetical Expressions

You can apply negation to entire parenthetical groups.

Example:
```
!(serial 1 to 6 && name P)
```
Selects atoms that do not have serial numbers between 1 and 6 while being named P.