e70cfc3b3ff31a9876df98f242162f60f839a7e9
brianlee
  Wed Jun 8 08:05:42 2022 -0700
Add doc back for hubClear (removed by 39e3bc63) & other hub loading parameters #29562

diff --git src/hg/htdocs/FAQ/FAQlink.html src/hg/htdocs/FAQ/FAQlink.html
index 5ccf205..b412092 100755
--- src/hg/htdocs/FAQ/FAQlink.html
+++ src/hg/htdocs/FAQ/FAQlink.html
@@ -234,30 +234,70 @@
 <p>
 To link to an assembly hub and display data on a non-natively supported genome, the same 
 parameters apply. To specify the intended genome assembly, instead of using <code>db=</code>,
 you must use <code>genome=araTha1</code>, where araTha1 is the assembly name set by
 your genomes.txt file in the line <code>genome araTha1</code>.</p>
 <pre><a href=../cgi-bin/hgTracks?genome=araTha1&hubUrl=http://genome.ucsc.edu/goldenPath/help/examples/hubExamples/hubAssembly/plantAraTha1/hub.txt>https://genome.ucsc.edu/cgi-bin/hgTracks?genome=araTha1&hubUrl=http://genome.ucsc.edu/goldenPath/help/examples/hubExamples/hubAssembly/plantAraTha1/hub.txt</a></pre>
 <p>
 To see the files behind that assembly hub, please visit the
 <a href="../goldenPath/help/examples/hubExamples/hubAssembly/plantAraTha1/">
 hub's directory</a>. For more information on assembly hubs in general, please see the
 <a href="http://genomewiki.ucsc.edu/index.php/Assembly_Hubs" target ="_blank">assembly hub wiki</a>, the <a
 href="../goldenPath/help/hgTrackHubHelp.html">track hub user guide</a>,
 or the <a href=../goldenPath/help/hubQuickStartAssembly.html>quick start guide
 to assembly hubs</a>.
 </p>
+<h6 id="hubClear">Use <code>hubClear=</code> to remove hubs at the same location</h6>
+<p>
+Another feature one can use in place of <code>hubUrl=</code> is
+<code>hubClear=</code>, which will load a hub while simultaneously disconnecting
+or clearing, hubs located at the same location. For example, adding
+<code>hubClear=http://university.edu/lab/folder/hub10.txt</code> would connect the
+referenced hub10.txt while simultaneously disconnecting any hubs that might be
+displayed from  the same <code>http://university.edu/lab/folder/</code> directory
+(for example, hub1.txt, hub2.txt, etc.). This feature can be useful for dynamically
+generated hubs that might collect in the browser otherwise.
+</p>
+<h6>Additional hub connection parameters</h6>
+<p>
+Alongside <code>hubUrl</code> and <code>hubClear</code> there are other parameters
+you can add to either if you wished, for instance, to attach an assembly hub and
+display the Gateway page, while also sharing your contact email.</p>
+<ul>
+<li id="hgHubConnect.remakeTrackHub"><code>hgHubConnect.remakeTrackHub=on</code>
+acts to connect when pointed to /hgHubConnect</li>
+<li id="hgHub_do_firstDb"><code>hgHub_do_firstDb=1</code>
+uses the first database in genomes.txt</li>
+<li id="hgHub_do_redirect"><code>hgHub_do_redirect=on</code>
+redirects the attached hub to the Gateway page</li>
+</ul>
+<p>
+By pointing the URL to <code>/cgi-bin/hgHubConnect</code> the hub would be connected to
+and then redirect to the Gateway page to display the page in <code>genomes.txt</code> defined
+by the <code>htmlPath ../newOrg.html</code> line. Here is an example:</p>
+<pre><code><a href="http://genome.ucsc.edu/cgi-bin/hgHubConnect?hgHub_do_redirect=on&hgHubConnect.remakeTrackHub=on&hgHub_do_firstDb=1&hubUrl=http://genome.ucsc.edu/goldenPath/help/examples/hubExamples/hubAssembly/plantAraTha1/hub.txt"
+target="_blank">http://genome.ucsc.edu/cgi-bin/hgHubConnect?hgHub_do_redirect=on&hgHubConnect.remakeTrackHub=on&hgHub_do_firstDb=1&<strong>hubUrl=http://genome.ucsc.edu/goldenPath/help/examples/hubExamples/hubAssembly/plantAraTha1/hub.txt</strong></a></code>
+</pre>
+<h6 id="genome">Use <code>genome=</code> for assembly hubs</h6>
+<p>
+There is also another way to connect an assembly hub using the <code>genome=</code> to arrive at
+the Gateway page if you know the genome in <code>genomes.txt</code> that you wish to display.
+For instance, the below link skips the redirection step, where your
+<code>hub.txt</code> contact email gets displayed, by pointing to the
+<code>/cgi-bin/hgGateway</code> page:</p>
+<pre><code><a href="http://genome.ucsc.edu/cgi-bin/hgGateway?genome=araTha1&hubUrl=http://genome.ucsc.edu/goldenPath/help/examples/hubExamples/hubAssembly/plantAraTha1/hub.txt"
+target="_blank"><strong>http://genome.ucsc.edu/cgi-bin/hgGateway?genome=araTha1&hubUrl=http://genome.ucsc.edu/goldenPath/help/examples/hubExamples/hubAssembly/plantAraTha1/hub.txt</strong></a> </code></pre>
  
 <a name="trackHubLoading"></a>
 <h3>Attaching a track hub to an assembly hub</h3>
 <h6>How do I attach a track hub to an assembly hub?</h6>
 <p>
 It is possible to attach a track hub to an assembly hub via the URL using a combination of the
 <code>hubUrl=</code> and <code>genome=</code> URL parameters. For example, using the following
 assembly hub and track hub:
 </p>
 <pre>
 <b>Arabidopsis thaliana assembly hub</b>
 https://genome.ucsc.edu/goldenPath/help/examples/hubExamples/hubPlants/cshl2013/hub.txt
 </pre>
 <pre>
 <b>ReMap2020 Reg. Atlas track hub</b>