A query directive transforms a list of zettel identifiers into a list of zettel identifiers.
It is only valid if a list of zettel identifiers is specified at the beginning of the query expression.
Otherwise the text of the directive is interpreted as a search expression.
For example, `CONTEXT` is interpreted as a full-text search for the word “context”.

Every query directive therefore consumes a list of zettel, and it produces a list of zettel according to the specific directive.

* [Context directive](00001007720300)
* [Thread Directive](00001007720500)
* [Ident directive](00001007720600)
* [Items directive](00001007720900)
* [Unlinked directive](00001007721200)