A filter operator is a predefined keyword attached to an individual step of a filter. It defines the particular action of that step.
Important: Each first step of a filter run not given any input titles receives the output of [all[tiddlers]] as its input.
The following table lists all core operators, the most common ones marked ✓. The last column indicates whether an operator allows negation using the ! prefix. For specifics as to each operator's negated output please refer to its documentation.
| Operator | Purpose | ✓ | ! |
|---|---|---|---|
| Order Operators | |||
| Listops Operators | |||
| String Operators | |||
| Tag Operators | |||
| Special Operators | |||
A typical step is written as [operator[parameter]], although not all of the operators need a parameter.
Most steps process the selection of titles that are supplied as their input, but a few construct an entirely new selection instead. For the exact rules, see Filter Syntax.