os-release: Add RELEASE_TYPE=

This will allow GUIs to customize their behavior a little based on the
type of release.

For example, an OS installer may display a warning/disclaimer if
RELEASE_TYPE=prerelease. The software updates app might be a bit more
insistent about upgrading to the next major release if
RELEASE_TYPE=stable than if RELEASE_TYPE=lts

diff --git a/man/os-release.xml b/man/os-release.xml
index afdb21fc57b92b710f0c507876e3e7e2b12a5774..32edc088df3dba7134f7cb38da23ff29270dce8e 100644 (file)
--- a/man/os-release.xml
+++ b/man/os-release.xml
@@ -325,6 +325,29 @@
 
           <xi:include href="version-info.xml" xpointer="v249"/></listitem>
         </varlistentry>
+
+        <varlistentry>
+          <term><varname>RELEASE_TYPE=</varname></term>
+
+          <listitem><para>A lower-case string (no spaces or other characters outside of 0-9, a-z, ".",
+          "_", and "-"), describing what kind of release this version of the OS is. Known values follow:
+          <literal>stable</literal> is for normal releases of the system, suitable for production use.
+          Generally, stable releases become end-of-life soon after the next major stable release is out.
+          Examples include Fedora 40, Ubuntu 23.10, OpenSUSE Tumbleweed, and Arch Linux.
+          <literal>lts</literal> is for long term support releases of the system, suitable for production
+          use and supported for an extended period of time. Generally, LTS releases continue to recieve
+          support even if newer major releases of the distribution are available. Examples include Ubuntu
+          24.04, Debian 12 Bookworm and RHEL 9.4.
+          <literal>pre-release</literal> is for unstable versions of the system, unsuitable for production
+          use, such as alpha, beta, or rolling unstable releases. Examples include Fedora Rawhide, Debian
+          Testing, Fedora 40 Beta, and GNOME OS Nightly.
+          If unset, or an unknown value, assume that the release is <literal>stable</literal>.</para>
+
+          <para>Examples: <literal>RELEASE_TYPE=pre-release</literal>, <literal>RELEASE_TYPE=lts</literal>.
+          </para>
+
+          <xi:include href="version-info.xml" xpointer="v257"/></listitem>
+        </varlistentry>
       </variablelist>
 
       <para>To summarize: if the image updates are built and shipped as comprehensive units,