Introduction
============

About
-----

.. include:: about.inc

Acknowledgements
----------------

This software was originally developed by Andy Kozubal at Los Alamos
National Laboratory (LANL). It was subsequently modified by William
Lupton, formerly at  the W. M. Keck Observatory (Keck), with
contributions by Greg White of the Stanford Linear Accelerator Center
National Accelerator Laboratory (SLAC-NAL).

Eric Norum, Janet Anderson, and Marty Kraimer (APS) made the initial
port to EPICS 3.14 that led to the 2.0.x series. Eric Norum and Andrew
Johnson (APS) provided lots of patches up to release 2.0.12.

Mark Rivers made a number of useful suggestions and tested version 2.1
with several sets of existing programs on various platforms. J. Lewis
Muir provided documentation patches.


Copying and Distribution
------------------------

The EPICS Sequencer is distributed subject to a Software License
Agreement found in the file LICENSE that is included with this
distribution.

.. include:: ../LICENSE

Note on Versions
----------------

This text is supposed to describe version 2.1. Version 2.1 adds
support for local definitions (including variable declarations) at all
levels, a significantly improved compiler that employs new lexer and
parser generators, lots of bug fixes, and a new *safe mode* to avoid
variable corruption due to race conditions.
See :ref:`Release_Notes_2.1.0` and :ref:`Release_Notes_2.0.99` for
details.

Version 2.0 differs from version 1.9 mainly in that sequencer
run-time code can run under any operating system for which an EPICS
OSI (Operating System Independent) layer is available, and message
systems other than channel access can be used. It depends on
libraries which are available only with EPICS R3.14.

An interim version 1.9.4 was made available to the EPICS community;
all new developments apart from major bug fixes will be based on
version 2.0.

Version 1.9 was written by Andy Kozubal, the original author of this
software. This version of the manual describes version 2.0, for
which the changes have been implemented by William Lupton of W. M.
Keck Observatory and Greg White of Stanford Linear Accelerator
Center (SLAC).

Versioning Policy
^^^^^^^^^^^^^^^^^

Starting with 2.0.0, the third digit is the patch level and will
be incremented each time a new version is released, no matter how
minor the changes. The second digit is the minor version number and
will be incremented each time functional changes are made. The
first digit is the major version number and will be incremented
only when major changes are made.

ToDo List
---------

.. todolist::