The parameter specifies zero or more fundamental categories using the following syntax:
| Category | Members | Sorted |
|---|---|---|
current | just the current tiddler | – |
missing | all non-existent tiddlers to which there is at least one hard link | no |
orphans | all tiddlers to which there are no hard links | by title |
shadows | all the shadow tiddlers that exist, including any that have been overridden with non-shadow tiddlers | no |
tags | all the tags in use on non-shadow tiddlers | no |
tiddlers | all the non-shadow tiddlers that exist | no |
If the parameter specifies more than one category, they are processed from left to right. The overall output is initially empty, and each category's output is dominantly appended to it in turn. Unrecognised categories contribute nothing to the output.
As a special case, if the parameter is empty, the output is simply a copy of the input. This can be useful when the parameter is soft.
The is operator is similar, but its scope is restricted to its input.