> > How can you have a generic XSLT client as described which will 
> > interoperate with all SRU servers, if the echoed XCQL were optional?
> You can't, it would be the choice of the implementor/database 
> owner to make the target available for that type of client.

That viewpoint breaks some of the fundamental philosophies behind
> In fact it might be desirable to exclude webb-browsers since 
> few servers could stand the load of being Slashdotted.

Well, if you want to exclude web-browsers then you probably want to
implement SRW rather than SRU (a server can support either or both of
these protocols, there is no interdependency). An SRW *may* return the
echoedSearchRetrieveRequest but there is no requirement to do so (and
XCQL is only mandatory within the echoedSearchRetrieveRequest). Ditto
for echoedScanRequest

Technically the echoedSearchRetrieveRequest is only "recommended" in SRU
rather than mandated - personally I think this should be strengthened -
so you could do an SRU without echoing the requests. You are however
cutting out the precisely the clients for which SRU was specifically