diff --git a/doc/source/reference/config.rst b/doc/source/reference/config.rst
index 7ad87c1710..58dbecbd12 100644
--- a/doc/source/reference/config.rst
+++ b/doc/source/reference/config.rst
@@ -59,6 +59,17 @@ As soon as a change containing a Zuul configuration change merges to
 any Zuul-managed repository, the new configuration takes effect
 immediately.
 
+.. _regex:
+
+Regular Expressions
+-------------------
+
+Many options accept literal strings or regular expressions.  In these
+cases, the regular expression matching starts at the beginning of the
+string as if there were an implicit ``^`` at the start of the regular
+expression. To match at an arbitrary position, prepend ``.*`` to the
+regular expression.
+
 .. _configuration-items:
 
 Configuration Items
diff --git a/doc/source/reference/job_def.rst b/doc/source/reference/job_def.rst
index f25ae88954..7a26871224 100644
--- a/doc/source/reference/job_def.rst
+++ b/doc/source/reference/job_def.rst
@@ -78,13 +78,6 @@ Here is an example of two job definitions:
            - name: test-node
              label: fedora
 
-.. warning::
-
-   Regular expression matching in Zuul *starts at the beginning of
-   the string*, i.e., as if there was an implicit ``^`` at the beginning
-   of the regular expression. To match at an arbitrary position, prepend
-   ``.*`` to the regular expression.
-
 .. attr:: job
 
    The following attributes are available on a job; all are optional
@@ -796,9 +789,10 @@ Here is an example of two job definitions:
 
    .. attr:: branches
 
-      A regular expression (or list of regular expressions) which
-      describe on what branches a job should run (or in the case of
-      variants, to alter the behavior of a job for a certain branch).
+      A :ref:`regular expression <regex>` (or list of regular
+      expressions) which describe on what branches a job should run
+      (or in the case of variants, to alter the behavior of a job for
+      a certain branch).
 
       This attribute is not inherited in the usual manner.  Instead,
       it is used to determine whether each variant on which it appears
@@ -864,7 +858,7 @@ Here is an example of two job definitions:
       specified files are modified.  Unlike **branches**, this value
       is subject to inheritance and overriding, so only the final
       value is used to determine if the job should run. This is a
-      regular expression or list of regular expressions.
+      :ref:`regular expression <regex>` or list of regular expressions.
 
    .. attr:: irrelevant-files
 
@@ -872,8 +866,8 @@ Here is an example of two job definitions:
       the job should run unless *all* of the files changed match this
       list.  In other words, if the regular expression ``docs/.*`` is
       supplied, then this job will not run if the only files changed
-      are in the docs directory.  A regular expression or list of
-      regular expressions.
+      are in the docs directory.  A :ref:`regular expression <regex>`
+      or list of regular expressions.
 
    .. attr:: match-on-config-updates
       :default: true
diff --git a/doc/source/reference/pragma_def.rst b/doc/source/reference/pragma_def.rst
index d26a42c5c2..6b5eefb3c0 100644
--- a/doc/source/reference/pragma_def.rst
+++ b/doc/source/reference/pragma_def.rst
@@ -38,7 +38,7 @@ pragma directives may not be set and then unset within the same file.
 
    .. attr:: implied-branches
 
-      This is a list of regular expressions, just as
+      This is a list of :ref:`regular expressions <regex>`, just as
       :attr:`job.branches`, which may be used to supply the value of
       the implied branch matcher for all jobs and project-templates in
       a file.
diff --git a/doc/source/reference/tenants.rst b/doc/source/reference/tenants.rst
index d05154dd02..8e8d5f070d 100644
--- a/doc/source/reference/tenants.rst
+++ b/doc/source/reference/tenants.rst
@@ -305,18 +305,18 @@ configuration. Some examples of tenant definitions are:
    .. attr:: allowed-labels
       :default: []
 
-      The list of labels (as strings or regular expressions) a tenant
-      can use in a job's nodeset. When set, this setting can be used
-      to restrict what labels a tenant can use.  Without this setting,
-      the tenant can use any labels.
+      The list of labels (as strings or :ref:`regular expressions <regex>`)
+      a tenant can use in a job's nodeset. When set, this setting can
+      be used to restrict what labels a tenant can use.  Without this
+      setting, the tenant can use any labels.
 
    .. attr:: disallowed-labels
       :default: []
 
-      The list of labels (as strings or regular expressions) a tenant
-      is forbidden to use in a job's nodeset. When set, this setting
-      can be used to restrict what labels a tenant can use.  Without
-      this setting, the tenant can use any labels permitted by
+      The list of labels (as strings or :ref:`regular expressions <regex>`)
+      a tenant is forbidden to use in a job's nodeset. When set, this
+      setting can be used to restrict what labels a tenant can use.
+      Without this setting, the tenant can use any labels permitted by
       :attr:`tenant.allowed-labels`.  This check is applied after the
       check for `allowed-labels` and may therefore be used to further
       restrict the set of permitted labels.