VMS DECwindows Transport Manual

This manual guides programmers in understanding, modifying, and extending the VMS DECwindows transport layer, particularly for VMS Version 5.3. It details the transport layer's architecture, which comprises network-independent transport-common functions (for buffering and queuing data) and network-specific transport components (for moving data over services like DECnet, TCP/IP, or local shared memory).

The document explains how X11 protocol requests, events, errors, and replies are generated, buffered, and transmitted. It describes the essential data structures—including XTPB, IXTCC, XTCC, XTDB, XTCQ, XTCB, and XTFT—that maintain the transport's state and connections, along with the communication queues facilitating data transfer. The manual provides descriptions of common transport routines that can be called, and outlines the transport-specific routines that developers must implement when integrating a third-party transport. It also offers a "cookbook" section with sample BLISS-32 code for implementing TCP/IP transport-specific components.