Four-Part Name Requirements for OLE DB Providers
Distributed queries can use four-part names only if the OLE DB provider supports the following:
The IDBSchemaRowset interface.
Restrictions on all the name parts that the provider supports in the IDBSchemaRowset interface. Restrictions are a mechanism defined in OLE DB for specifying the search criteria for metadata queries using the OLE DB schema rowsets.
The literals DBLITERAL_CATALOG_SEPARATOR, DBLITERAL_SCHEMA_SEPARATOR, and DBLITERAL_QUOTE in the IDBInfo interface. SQL Server 2005 uses defaults, '.' for catalog and schema separator and the double-quotation character for string literal delimiter. This may not work with providers that do not support these literals.
SQL Server also consumes the Unicode string literal prefix and Unicode string literal suffix from DBSCHEMA_PROVIDER_TYPES, if they are supplied by the provider.
If an OLE DB provider does not meet these requirements, the provider can be referenced only by using pass-through queries in the OPENDATASOURCE or OPENROWSET function.