select is a type of filter used to select a subset of tiddlers from a collection of tiddlers. You may select by an attribute and some value of that attribute, in a few different forms. We'll use the example of tiddler modified time to expalin.

Exact

This will get those tiddlers which have a modified time of exactly midnight at the start of May 9th, 2009.

Negate

This will get those tiddlers which have a modified time of any time except exactly midnight at the start of May 9th, 2009.

Greater

This will get those tiddlers which have a modified time newer than (greater than, exclusive) midnight at the start of May 9th, 2009.

Lesser

This will get those tiddlers which have a modified time older than (greater than, exclusive) midnight at the start of May 9th, 2009.

When performing comparisons (i.e. using < or >) TiddlyWeb will canonicalize the attribute to an appropriate form based on (the extensible) ATTRIBUTE_SORT_KEY in tiddlyweb.filters.sort.