--- a/galaxy-conf/ValueDistribution.xml	Mon Apr 09 11:50:23 2012 -0400
+++ b/galaxy-conf/ValueDistribution.xml	Wed Apr 25 16:53:48 2012 -0400
@@ -1,6 +1,16 @@
 <tool id="ValueDistribution" name="Compute the value distribution" version="1.0.0">
   <description>of a (Big)Wig file</description>
-  <command interpreter="sh">galaxyToolRunner.sh wigmath.ValueDistribution -i $input --max $max --min $min -n $bins -o $output</command>
+  <command interpreter="sh">galaxyToolRunner.sh wigmath.ValueDistribution -i $input 
+    #if str( $min ) != ''
+      --min $min
+    #end if
+    
+    #if str( $max ) != ''
+      --max $max
+    #end if
+    
+    -n $bins -o $output
+  </command>
   <inputs>
       <param format="bigwig,wig" name="input" type="data" label="(Big)Wig file" />
       <param name="min" type="float" optional="true" label="Minimum bin value (optional)" />
@@ -12,5 +22,32 @@
   </outputs>
   
 <help>
+  
+This tool computes a histogram of the values in a Wig file, as well as the moments of the distribution.
+
+-----
+
+**Syntax**
+
+- **Input data** is the genomic data used to compute the histogram.
+- **Minimum bin value** is the smallest bin. If unset, it is equal to the minimum value in the input data
+- **Maximum bin value** is the largest bin. If unset, it is equal to the maximum value in the input data
+- **Number of bins** is the number of bins to use. The bin size will be equal to (max - min) / (# bins).
+
+-----
+
+**Output**
+
+The output is in 2-column tabular format, where the first column represents the lower edge of a bin inteval and the second column represents the number of values that fell in that bin. For example if the **minimum bin value** is 0, the **maximum bin value** is 0.3, and the **number of bins** is 3, then the following output might be produced ::
+
+  bin       count
+  &lt;0        3
+  0         1
+  0.1       10
+  0.2       4
+  &gt;0.3      12
+  
+where there were 3 values in (-inf, 0), 1 value in [0, 0.1), 10 values in [0.1, 0.2), 4 values in [0.2, 0.3), and 12 values in [0.3, inf).
+  
 </help>
 </tool>