791ff217c3dcd05a79344eb2c9e335fe40d7ab7c
lrnassar
  Tue Dec 8 13:41:41 2020 -0800
Adding a note about default URL parameter in wiki refs #26650

diff --git src/hg/htdocs/FAQ/FAQlink.html src/hg/htdocs/FAQ/FAQlink.html
index 337296d..2ffa470 100755
--- src/hg/htdocs/FAQ/FAQlink.html
+++ src/hg/htdocs/FAQ/FAQlink.html
@@ -1,29 +1,29 @@
 <!DOCTYPE html>
 <!--#set var="TITLE" value="Genome Browser FAQ" -->
 <!--#set var="ROOT" value=".." -->
 
 <!-- Relative paths to support mirror sites with non-standard GB docs install -->
 <!--#include virtual="$ROOT/inc/gbPageStart.html" -->
 
 <h1>Frequently Asked Questions: Linking to the Genome Browser</h1>
 
 <h2>Topics</h2>
 
 <ul>
 <li><a href="#link1">Creating a sharable URL to view specific tracks</a></li>
-<li><a href="#link2">Linking to the Browser at a specific position</a></li>
+<li><a href="#link2">Linking to the Browser at a specific position, or default position</a></li>
 <li><a href="#zoomVariant">Zooming in or out using a link to an HGVS identifier</a></li>
 <li><a href="#trackViz">Setting track visibility via URL</a></li>
 <li><a href="#custUrl">Loading Custom Tracks with the URL</a></li>
 <li><a href="#hubUrl">Loading Track Hubs and Assembly Hubs with the URL</a></li>
 <li><a href="#genes">Linking to gene-specific information</a></li>
 <li><a href="#hgsid">The hgsid parameter</a></li>
 <li><a href="#moreInfo">Additional URL parameters</a></li>
 </ul>
 
 <a name="link1"></a>
 <h2>Creating a sharable URL to view specific tracks</h2>
 <h6>How do I create a link to the Genome Browser to share my data?</h6>
 <p> 
 The easiest way to save and share tracks from the URL is by
 <a href="../cgi-bin/hgLogin" TARGET="_blank">logging in</a> to your Genome Browser account and
@@ -48,51 +48,61 @@
 <p>
 This longer format has the flexibility of replacing &quot;hgTracks&quot; with different tool names to share 
 saved settings on the Table Browser (hgTables), Variant Annotation Integrator (hgVai), or Data 
 Integrator (hgIntegrator). This will preserve your option selections and can be useful to share.
 The following format will bring the recipient to a user's custom Table Browser selections:</p>
 <p><code>http://genome.ucsc.edu/cgi-bin/hgTables?hgS_doOtherUser=submit&amp;hgS_otherUserName=&lt;userName&gt;&amp;hgS_otherUserSessionName=&lt;sessionName&gt;</code></p>
 
 <p>Both session link formats have the advantage of being able to add URL parameters to the end.
 The shorter link format requires a question mark before any URL parameters, with ampersand 
 characters separating different parameters like so: </p>
 <p><code><a href=http://genome.ucsc.edu/s/view/clinicalzoom?textSize=18>http://genome.ucsc.edu/s/view/clinicalzoom?textSize=18</a></code></p>
 <p>Both formats require an ampersand between each additional parameter, seen in the longer format like so:</p>
 <p><code><a href=http://genome.ucsc.edu/cgi-bin/hgTracks?hgS_doOtherUser=submit&amp;hgS_otherUserName=view&amp;hgS_otherUserSessionName=clinicalzoom&amp;textSize=18>http://genome.ucsc.edu/cgi-bin/hgTracks?hgS_doOtherUser=submit&amp;hgS_otherUserName=view&amp;hgS_otherUserSessionName=clinicalzoom&amp;textSize=18</a></code></p>
 
 <a name="link2"></a>
-<h2>Linking to the Browser at a specific position</h2>
+<h2>Linking to the Browser at a specific position, or default position</h2>
 <h6>How do I make a link to a specific genome, position, or HGVS variant?</h6>
 <p>
 You can link to a specific genome assembly and position in the Genome Browser using a URL with
 the <code>db=</code> and <code>position=</code> parameters.</p>
 <p><code>http://genome.ucsc.edu/cgi-bin/hgTracks?db=&lt;assembly&gt;&position=&lt;position&gt;</code></p>
 <p>
 Where:</p>
 <ul>
   <li>
   <code>db</code> - designates a specific genome assembly. For example, <code>db=hg19</code> 
   refers to the Feb. 2009 human genome release. For a list of db parameter values that 
   correspond to UCSC assemblies, see the <a href="FAQreleases.html#release1">list of UCSC 
   releases</a>.</li>
   <li><code>position</code> - can be any search term for the genome specified, including
   a position range or a gene identifier. This often takes the form of
   <code>position=chr1:35000-40000</code>.</li>
 </ul>
 <p>The following link is an example of a URL that declares assembly and position:</p>
 <p><code><a href="../cgi-bin/hgTracks?db=hg19&position=chr1:35000-40000">http://genome.ucsc.edu/cgi-bin/hgTracks?db=hg19&position=chr1:35000-40000</a></code></p>
 
+<h6>How do I make a link to the default position of a genome?</h6>
+<p>
+You can link directly to the default position of an assembly by passing the 
+<code>position=default</code> parameter. This can be helpful in cases where
+a track exists on multiple assemblies, and you want to build links to each of them. If no
+position variable is passed, the Genome Browser assumes the default position for the 
+default assembly (hg38).</p>
+<p>
+Here is an example which opens the uniprot track at the default position for sacCer3:</p>
+<p><code><a href="/cgi-bin/hgTrackUi?db=sacCer3&g=uniprot&position=default">http://genome.ucsc.edu/cgi-bin/hgTrackUi?db=sacCer3&g=uniprot&position=default</a></code></p>
 
 <a name="zoomVariant"></a>
 <h2>Zooming in or out with a link &mdash; HGVS </h2>
 <h6>How do I zoom out using a link to a HGVS identifier?</h6>
 <p>
 To link to a specific HGVS identifier, you can construct a link with the HGVS identifier
 in the position field instead of coordinates. The default padding is 5bp on either side,
 but you can always zoom in or out with <code>hgt.out1=submit</code> or <code>hgt.in1=submit</code>.
 The numbers 1 through 4 zoom in or out corresponding to the buttons above the track window.
 The following lists the zoom levels of each number, applicable to zooming in or out:</p>
 <ul>
 <li><code>hgt.out1=submit</code> zooms out 1.5x</li>
 <li><code>hgt.out2=submit</code> zooms out 3x</li>
 <li><code>hgt.out3=submit</code> zooms out 10x
 <li><code>hgt.out4=submit</code> zooms out 100x</li>