a3d3c1d713678d6306a96be69a1df93a82e0dfdd
max
  Thu May 20 01:48:01 2021 -0700
adding chromStart=chromEnd case to BED docs, refs #24836

diff --git src/hg/htdocs/FAQ/FAQformat.html src/hg/htdocs/FAQ/FAQformat.html
index 5d50cd0..da83f65 100755
--- src/hg/htdocs/FAQ/FAQformat.html
+++ src/hg/htdocs/FAQ/FAQformat.html
@@ -100,31 +100,34 @@
 The first three required BED fields are: </p>
 <ol>
   <li> 
   <strong>chrom</strong> - The name of the chromosome (e.g. chr3, chrY, chr2_random) or scaffold 
   (e.g.  scaffold10671).</li>
   <li>
   <strong>chromStart</strong> - The starting position of the feature in the chromosome or scaffold. 
   The first base in a chromosome is numbered 0.</li>
   <li>
   <strong>chromEnd</strong> - The ending position of the feature in the chromosome or scaffold. The 
   <em>chromEnd</em> base is not included in the display of the feature, however,
   the number in <a href="FAQtracks#tracks1">position format</a> will be represented. For example,
   the first 100 bases of chromosome 1 are defined as <em>chrom=1, chromStart=0, chromEnd=100</em>,
   and span the bases numbered 0-99 in our software (not 0-100), but will represent the
   position notation chr1:1-100. Read more
-  <a href="http://genome.ucsc.edu/blog/the-ucsc-genome-browser-coordinate-counting-systems/">here</a>.</li>
+  <a href="http://genome.ucsc.edu/blog/the-ucsc-genome-browser-coordinate-counting-systems/">here</a>. 
+  <br><em>chromStart</em> and <em>chromEnd</em> can be identical, creating a feature of length 0, commonly
+  used for insertions. For example, use <em>chromStart=0, chromEnd=0</em> to represent an insertion before the
+  first nucleotide of a chromosome.</li>
 </ol>
 <p>The 9 additional optional BED fields are:</p>
 <ol start=4>
   <li>
   <strong>name</strong> - Defines the name of the BED line. This label is displayed to the left of 
   the BED line in the Genome Browser window when the track is open to full display mode or directly 
   to the left of the item in pack mode.</li>
   <li>
   <strong>score</strong> - A score between 0 and 1000. If the track line <em>useScore</em> attribute
   is set to 1 for this annotation data set, the <em>score</em> value will determine the level of 
   gray in which this feature is displayed (higher numbers = darker gray). This table shows the 
   Genome Browser's translation of BED score values into shades of gray:
   <table>
     <tr>
       <td>shade</td>