a7f53180b993efb1a7484c732f9b8693e666fc76
lrnassar
  Fri Jun 16 15:18:02 2023 -0700
Removing a word since it can confuse and adds no value to the example, refs #31241

diff --git src/hg/htdocs/goldenPath/help/chain.html src/hg/htdocs/goldenPath/help/chain.html
index cf1b183..6d5e546 100755
--- src/hg/htdocs/goldenPath/help/chain.html
+++ src/hg/htdocs/goldenPath/help/chain.html
@@ -1,112 +1,112 @@
 <!DOCTYPE html>
 <!--#set var="TITLE" value="Genome Browser Chain Format" -->
 <!--#set var="ROOT" value="../.." -->
 
 <!-- Relative paths to support mirror sites with non-standard GB docs install -->
 <!--#include virtual="$ROOT/inc/gbPageStart.html" -->
 
 <h1>Chain Format</h1> 
 <p> 
 The chain format describes a pairwise alignment that allow gaps in both sequences simultaneously. 
 Each set of chain alignments starts with a header line, contains one or more alignment data lines, 
 and terminates with a blank line. The format is deliberately quite dense.</p>  
 <p> 
 <strong><em>Example:</em></strong></p>
 <pre><code>    chain 4900 chrY 58368225 + 25985403 25985638 chr5 151006098 - 43257292 43257528 1
      9       1       0
      10      0       5
      61      4       0
      16      0       4
      42      3       0
      16      0       8
      14      1       0
      3       7       0
      48
 
      chain 4900 chrY 58368225 + 25985406 25985566 chr5 151006098 - 43549808 43549970 2
      16      0       2
      60      4       0
      10      0       4
      70</code></pre> 
 <p>
 <strong>Header Lines</strong> 
 <p>
 <pre><code>    <strong>chain</strong> <em>score</em> <em>tName</em> <em>tSize</em> <em>tStrand</em> <em>tStart</em> <em>tEnd</em> <em>qName</em> <em>qSize</em> <em>qStrand</em> <em>qStart</em> <em>qEnd</em> <em>id</em> </code></pre> 
 <p>
 The initial header line starts with the keyword <strong><code>chain</code></strong>, followed by 
 11 required attribute values, and ends with a blank line. The attributes include: 
 <ul> 
   <li> 
   <strong><code>score</code></em></strong> -- chain score</li>
   <li>
   <strong><code>tName</code></strong> -- chromosome (reference/target sequence)</li>
   <li>
   <strong><code>tSize</code></strong> -- chromosome size (reference/target sequence)</li>
   <li>
   <strong><code>tStrand</code></strong> -- strand (reference/target sequence)</li>
   <li>
   <strong><code>tStart</code></strong> -- alignment start position (reference/target sequence)</li>
   <li>
   <strong><code>tEnd</code></strong> -- alignment end position (reference/target sequence)</li>
   <li>
   <strong><code>qName</code></strong> -- chromosome (query sequence)</li>
   <li>
   <strong><code>qSize</code></strong> -- chromosome size (query sequence)</li>
   <li>
   <strong><code>qStrand</code></strong> -- strand (query sequence)</li>
   <li>
   <strong><code>qStart</code></strong> -- alignment start position (query sequence)</li>
   <li>
   <strong><code>qEnd</code></strong> -- alignment end position (query sequence)</li>
   <li>
   <strong><code>id</code></strong> -- chain ID</li>
 </ul> 
 <p> 
 The alignment start and end positions are represented as zero-based half-open intervals. For 
 example, the first 100 bases of a sequence would be represented with start position = 0 and end 
 position = 100, and the next 100 bases would be represented as start position = 100 and end 
 position = 200. When the strand value is &quot;-&quot;, position coordinates are listed in terms of 
 the reverse-complemented sequence.</p> 
 <p>
 <strong>Alignment Data Lines</strong></p> 
 <p> 
 Alignment data lines contain three required attribute values:<p>
 <pre>    <em>size</em> <em>dt</em> <em>dq</em></pre>
 <ul> 
   <li> 
   <strong><code>size</code></strong> -- the size of the ungapped alignment</li>
   <li> 
   <strong><code>dt</code></strong> -- the difference between the end of this block and the beginning of 
   the next block (reference/target sequence)</li>
   <li> 
   <strong><code>dq</code></strong> -- the difference between the end of this block and the beginning of 
   the next block (query sequence)</li>
 </ul> 
 <p> 
 NOTE: The last line of the alignment section contains only one number: the ungapped alignment size 
 of the last block.</p>
 
 <a name="rearrangement"></a> 
 <h3>&quot;Snake&quot; rearrangement display</h3>
 <p>
 Rearrangement display, sometimes called snakes display, is an alternative way to view pairwise alignemnts.
 It is available for PSL and chain format tracks.</p>
 <p>
 Rearrangement display is a representation of the path that the sequence follows in the &quot;other&quot; sequence. 
 You start in the upper left and move to the right, following the lines if you come to the end of a block. If a block 
 is red, which means it is a match on the negative strand, then you reverse your course and start going from right to left.
 The gray lines mean there are no bases in the other sequence between the blocks. Orange lines means there are some 
 bases in there that are not aligning.</p>
 <p>The display type can be enabled on the track configuration page of eligible tracks. Below are two examples for clarity.</p>
 <p>
 <div class="text-left">
   <img src="../../images/rearrangementExample1.png" alt="Rearrangement display example 1" width='55%'>
 </div><br>
 This example shows a tandem duplication on CDH1 which duplicates 3 exons.</p>
 <p>
 <div class="text-left">
   <img src="../../images/rearrangementExample2.png" alt="Rearrangement display example 2" width='55%'>
 </div><br>
-This example shows a polymorphic inversion, which can be identified by the red colored sequence.</p>
+This example shows an inversion, which can be identified by the red colored sequence.</p>
 
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