1 files changed, 41 insertions, 2 deletions

diff --git a/doc/developer-guidelines.sgml b/doc/developer-guidelines.sgml
index 6e35615..f5e376a 100644
--- a/doc/developer-guidelines.sgml
+++ b/doc/developer-guidelines.sgml
@@ -99,7 +99,7 @@
         <literallayout>
         gnu make 3.79
         automake 1.6
-        autoconf 2.52
+        autoconf 2.54
         gettext 0.11.5
         </literallayout>
 
@@ -235,6 +235,42 @@
       
                 </section>
 
+                <section id="thresholdformat"><title>Threshold range format</title>
+                <para>Thresholds ranges define the warning and critical levels for plugins to 
+                alert on. The theory is that the plugin will do some sort of check which returns
+                back a numerical value, or metric, which is then compared to the warning and 
+                critical thresholds.
+                This is the generalised format for threshold ranges:</para>
+
+                <literallayout>
+                [@]start:end
+                </literallayout>
+        
+                <para>Notes:</para>
+                <orderedlist>
+                <listitem><para>start < end</para>
+                        </listitem>
+                <listitem><para>start and ":" is not required if start=0</para>
+                        </listitem>
+                <listitem><para>if range is of format "start:" and end is not specified, 
+                        assume end is infinity</para>
+                        </listitem>
+                <listitem><para>to specify negative infinity, use "~"</para>
+                        </listitem>
+                <listitem><para>alert is raised if metric is outside start and end range
+                        (inclusive of endpoints)</para>
+                        </listitem>
+                <listitem><para>if range starts with "@", then alert if inside this range
+                        (inclusive of endpoints)</para>
+                        </listitem>
+                </orderedlist>
+                
+                <para>Note: Not all plugins are coded to expect ranges in this format. It is
+                planned for a future release to
+                provide standard libraries to parse and compare metrics against ranges. There
+                will also be some work in providing multiple metrics.</para>
+                </section>
+
                 <section><title>Performance data</title>
                 <para>Performance data is defined by Nagios as "everything after the | of the plugin output" -
                 please refer to Nagios documentation for information on capturing this data to logfiles.
@@ -267,9 +303,12 @@
                         </listitem>
                 <listitem><para>min and max are not required if UOM=%</para>
                         </listitem>
-                <listitem><para>value, crit, warn, max and min in class [-0-9.]. Must all be the
+                <listitem><para>value, min and max in class [-0-9.]. Must all be the
                         same UOM</para>
                         </listitem>
+                <listitem><para>warn and crit are in the range format (see 
+                        <xref linkend="thresholdformat">)</para>
+                        </listitem>
                 <listitem><para>UOM (unit of measurement) is one of:</para>
                         <orderedlist>
                         <listitem><para>no unit specified - assume a number (int or float)