== Using SL Yum Variables ==
The yum application is highly extensible via its plugin and variable APIs.

The Scientific Linux repos utilize the following yum variables:
|========================================================================================================================
|Name          | Purpose                                 | Source                                       | Example Values
|$basearch     | Describe the architecture of the system | yum determines automatically from sl-release | x86_64
|$releasever   | What is the 'vendor neutral' version    | yum determines automatically from sl-release | 7.0  7
|$slreleasever | What is the version of SL               | Provided by sl-release or yum-conf-7x        | 7x 7rolling 7.0
|========================================================================================================================

TIP: You can define any variable you want in yum by setting it in +/etc/yum/vars/+
     Simply +echo value > /etc/yum/vars/name+ an you've got +$name+ defined.

For Scientific Linux 7 we've adopted a stronger use of yum variables to help
simplify the customization for individual administrators.

Now any customizations to your repo files, such as use of local mirrors, are
easily kept between releases as the SL provided repository files are not
expected to change.

This does, however, provide unexpected behavior during our Release
Candidate process.  If the +7x+ config is enabled, you will point to the +7x+
repo rather than the Release Candidate repo.  At that time the +7x+ repo will
contain some older software than the Release Candidate.

[[rc-users-readme]]
[[slver-state]]
.Chart of $slreleasever
|=================================================================================================================================
| System State    | SL7 Alpha/Beta | SL7 Alpha/Beta +7x | SL7 RC | SL7 RC +7x | SL7 GA | SL7 GA +7x | SL7 GA removed yum-conf-sl7x
| Fresh Install   | 7rolling       | 7rolling           | 7.0    | 7x         | 7.0    | 7x         | 7.0
| Upgrade From 7.0| 7rolling       | 7rolling           | 7.1    | 7x         | 7.1    | 7x         | 7.1 
|=================================================================================================================================

IMPORTANT: Users wishing to test packages from the Release Candidate during
           the Release Candidate process may need to remove yum-conf-sl7x. +
           As per the chart above, if +yum-conf-sl7x+ is installed, your system
           will point towards the 7x repos rather than the as yet unreleased
           Release Candidate.

CAUTION: If you remove +yum-conf-sl7x+ during the Release Candidate process,
         you should consider reinstalling it after the offical release.

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