Searching in WebDAV

	PROPFIND	REPORT	SEARCH
grammar discovery	n/a	Using computed property DAV:supported-report-set .	Using OPTIONS method ("DASL" header).
selection	Using PROPFIND with DAV:prop.	Depends on the report type. For instance, DAV:version-tree works similar to PROPFIND.	Depends on the search grammar. For instance, DAV:basicsearch works similar to PROPFIND.
sorting	PROPFIND preserves the sort order of collection members (if the collection is sorted).	Depends on the report type.	Depends on the search grammar. For instance, DAV:basicsearch allows sorting by property values (ascending and descending).
scoping and depth	PROPFIND supports depth 0, 1 and infinity (using the Depth header). The scope if defined by the request URI.	Depends on the report type.	Depends on the search grammar. For instance, DAV:basicsearch allows specification of both a search resource and depth (meaning that the SEARCH request can be sent to a resource different from the search scope).
restricting result size	n/a	Depends on the report type.	Depends on the search grammar. For instance, DAV:basicsearch allows restricting the number of results.
discovery of searchable properties	n/a	Depends on the report type.	Depends on the search grammar. Older versions of the DASL spec attempted to define query schemas, but this was dropped.

Conclusions:

There are three methods with partly overlapping features: PROPFIND (defined in RFC2518), REPORT (defined in the soon-to-appear deltaV RFC) and SEARCH (expired draft).
REPORT and SEARCH seem to be almost identical in features -- both just define frameworks into which query/report grammars can be plugged in.
There doesn't seem to be anything in the DASL framework that couldn't be done with REPORT. In fact, query grammar (REPORT) discovery seems to have a more elegant solution.

Proposal: drop work on DASL. Instead define an (extensible) equivalent of DAV:basicseach, with the following additional features:

discovery of searchable properties
discovery of supported constructs in the grammar
better signaling of execution errors (non-searchable properties, not recognized grammar constructs)
definition of a mandatory subset of query grammar features

Publish this as separate RFC, or possibly move it into RFC2518++.