[Commentor] LC-2834 Tim Berners-Lee (archived comment) [Comment] 4.5.6. You allow servers which do not support PUT or PATCH or POST. Why? A client using such a server will have no write ability at all, and so your spec as a protocol delivers zero value on top of HTTP GET. Suggest change all to MUST, or make two levels of server, one which supports PUT and PATCH and no collections, and one which supports everything. ... 4.8 PATCH is optional. Suggest a MUST. PATCH is to first order the only thing LDP provides over WebDav. 4.8.2 MUST Suggest specify a the subset of sparql-update we use at the moment as a mandatory patch format to get basic interop, with possible later extension to other languages. ******* Something I mentioned in a mail a long time ago is the necessity of doing atomic flag (P/V) operations with a PATCH. To recap, you have to be able to do a form of DELETE triple(s) which will FAIL and prevent any corresponding INSERT from happening. This is top be able to allocate shared resources. Eg DELETE { :x :nextID 4 } INSERT DATA { ?x :nexID 5 }. Hmm. Maybe this is covered by the ETag system sufficiently. If so, the case should be given as an worked example and put in as a test case. A collaborative system which allows atomic flag setting is fundamentally more valuable than one which doesn't. [Commentor reply] tocheck [Working Group decision] 
The LDP specification brings several features such as paging and containers that are useful even in case of a read-only server. As for PATCH, everybody wants it but given the lack of a standard PATCH format and the WG timeframe it is unpractical for LDP to make PATCH mandatory. The WG is however committed to encourage support for PATCH and will do so via the LDP Best Practices and Guidelines document the WG plans to publish as a Note. As soon as a standard PATCH format is available the WG will revise the LDP spec to make use of it.