--- a/farol/templates/document/edit_revision.j2	Thu Oct 23 16:18:30 2014 +0200
+++ b/farol/templates/document/edit_revision.j2	Thu Oct 23 16:32:33 2014 +0200
@@ -30,7 +30,7 @@
 {% block content %}
 <p><strong>Revision</strong> contains all the elements required to track the evolution of a CVRF document. Each change to a CVRF document should be accompanied by <strong>Number</strong>, <strong>Date</strong>, and <strong>Description</strong> elements.</p>
 <form role="form" method="POST">
-  {% call textinput("number", "Number", "a.b.c.d", number, required=True) %}
+  {% call textinput("number", "Number", "a.b.c.d", number, required=True, regex='(0|[1-9][0-9]*)(\.(0|[1-9][0-9]*)){0,3}') %}
   <p><strong>Number</strong> should contain the numeric version of the document. Like the <strong>Version</strong> element above, it is a numeric tokenized field of the format “nn” with up to four fields “nn.nn.nn.nn”. It is recommended that this be a monotonically increasing value. Minor revisions should be used for less-significant changes (for example, <samp>1.0.0.0</samp> to <samp>1.0.0.1</samp>). Major, actionable changes should lead to a major increase of the version number (for example, <samp>1.0</samp> to <samp>2.0</samp>).</p>
   <p>Examples of such changes include:</p>
   <ul>