Sets the search filter (facets, or other). The filter values must obey the predicate grammar.
Optional. It may be set several times (in which case all filters are evaluated in an AND fashion).
The AND, NOT and OR operators are available.
Items filtering is done by items type (an item type correspond to an afs:set element in the indexing feed).
If some items of a given item type match the query, then filtering will be applied on this type of item. Items that do not match will be removed from the document, with all their child items if applicable.
A full-text query that contains several words can retrieve documents that contain occurrences of these words spread across different document items along the same branch of the document tree.
afs:filter=a>b&afs:filter=c<d is equivalent to afs:filter=(a>b)and(c<d).
afs:filter=not(category=a) will hide results with a value a for facet category.