A step represents a single operation within a filter.
In programming terms, it is akin to a function call to which the step's input is passed as an implicit parameter. A step's output is a selection that contributes to a run and hence to the entire filter expression that contains it.
The step's operator is drawn from a list of predefined keywords, which can be extended by plugins. Any unrecognised operator is treated as if it was the suffix to the
field operator. If a step's operator is omitted altogether, it defaults to
The suffix is additional text, often the name of a field, that extends the meaning of certain operators.
Many steps require an explicit parameter value, also known as an operand, that further defines what the step is to do.
New in: 5.1.23 Some steps accept multiple parameters which are separated by a