Thanks for the explanation. I've done some tests with the sample database of SA 11.0.1.2527 and 12.0.1.3324 and have not had issues with the 4-part syntax - and according to your note, both versions are fixed in that respect.

FWIW, these is a short test script - here for the SA11 demo database:

:::SQL
-- add linked server (DSN-less) with default dba login
exec sp_addlinkedserver 'SVR_SA', 'SA Test', 'SAOLEDB.11', null,
   null, 'ENG=demo11;DBN=demo;LINKS=TCPIP;CON=MSLinkedSvr', null
exec sp_addlinkedsrvlogin 'SVR_SA', 'false', null, 'dba', 'sql'

-- set necessary options
exec sp_serveroption 'SVR_SA', 'collation compatible', 'true'
exec sp_serveroption 'SVR_SA', 'data access', 'true'
exec sp_serveroption 'SVR_SA', 'rpc', 'true'
exec sp_serveroption 'SVR_SA', 'rpc out', 'true'

-- check results
exec sp_helpserver 'SVR_SA'
exec sp_helplinkedsrvlogin 'SVR_SA'

-- test queries in 4-part syntax
select * from SVR_SA..groupo.Contacts
exec SVR_SA..groupo.ShowContacts 1

-- drop linked server
exec sp_droplinkedsrvlogin 'SVR_SA', null
exec sp_dropserver 'SVR_SA'

Is there any more info on the first CR you mentioned? (The public description seems empty.)

IIRC, the MS DTC setup was one of the biggest hurdles to get the LinkedServer feature running against SQL Anywhere, so more info would be welcome. (In general, I'm just doing read access against SQL Anywhere, so I usually would think there would be no need for distributed transactions at all. FWIW, the above test seems to work without having to setup MS DTC on my box...)

Yes, you are correct, the public description for the first CR is indeed empty. The problem had to do with the order in which MS SQL Server issues the two-phase commit request and the connection close request. Since the actual problem was out of the user's control, the public description was left empty. Suffice it to say that both fixes are necessary to get Linked Servers to fully work. Your test does not perform updates so DTC probably is not necessary.