DECnet-Plus

This document, "DECnet-Plus DECdts Programming" (November 1996), is a programming manual for the Digital Distributed Time Service (DECdts). DECdts is a network-wide service that synchronizes system clocks across OpenVMS and Digital UNIX operating systems using Coordinated Universal Time (UTC).

The manual primarily serves two audiences:

1. Programmers using the DECdts API: It provides reference information for C programming routines to obtain, convert, and calculate time values. This includes handling absolute and relative times, various time structures (like utc, tm, timespec, and OpenVMS time), converting between binary and ASCII representations, and obtaining time zone information. A C programming example is included.
2. Programmers developing Time-Provider (TP) interfaces: It describes the Time-Provider Interface (TPI), which allows DECdts servers to integrate with external time-provider hardware. This section details the interprocess communication (using OpenVMS mailboxes or UNIX domain sockets), message types (request, control, data) and their fields, and the algorithms for both the DECdts server and the TP process.

The document targets developers working on DECnet-Plus for OpenVMS (Version 7.1) and DECnet/OSI for Digital UNIX (Version 4.0) systems.