MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 2: An Introduction to SQL and ODBC
In looking at the database access components described in the preceding section, it turns out that two of them—programming interfaces and data stream protocols—are good candidates for standardization. The other two components—IPC mechanism and network protocols—not only reside at too low a level but they are both highly dependent on the network and operating system. There is also a third approach—gateways—that provides possibilities for standardization.