689349fca5a4865a1891db8cd39d392657b2b09b
jcasper
  Wed Apr 22 02:54:09 2026 -0700
Replacing the subtrackUrl setting for faceted composites with subtrackUrls,
which supports outlinks in multiple fields.  refs #36320

diff --git src/hg/htdocs/goldenPath/help/trackDb/trackDbLibrary.shtml src/hg/htdocs/goldenPath/help/trackDb/trackDbLibrary.shtml
index caaa4a44e5a..78aa2452b35 100644
--- src/hg/htdocs/goldenPath/help/trackDb/trackDbLibrary.shtml
+++ src/hg/htdocs/goldenPath/help/trackDb/trackDbLibrary.shtml
@@ -6855,43 +6855,43 @@
 <DIV class="defaultSortField"><span class="types faceted composite"></span>
 <div class="format"><code>defaultSortField &lt;name&gt;</code></div>
 <p>
 This optional setting chooses which field in the metadata table will be used to sort the table
 of subtracks when the page is first loaded.  The name should match the field name in the first
 line of the metadata tsv file.  If there is no match, or if this setting is absent, the first
 field in the metadata tsv file is used as the default sort field.
 </p>
 <p>Example:
 <pre>
 defaultSortField tissue
 </pre>
 </p>
 </div>
 
-<DIV class="subtrackUrl"><span class="types faceted composite"></span>
-<div class="format"><code>subtrackUrl &lt;url&gt;</code></div>
+<DIV class="subtrackUrls"><span class="types faceted composite"></span>
+<div class="format"><code>subtrackUrls &lt;field1&gt;=&lt;url1&gt; &lt;field2&gt;=&lt;url2&gt; ...</code></div>
 <p>
 For some faceted composites, each subtrack is associated with a particular cell line or
 other accession that is described in more detail at another resource (e.g. ENCODE or SRA).
-This optional setting specifies a remote URL for linking out to those resources.  When
-it is set, the names in the primary key column of the metadata TSV file will be turned into
-hyperlinks to that resource.  If the URL includes the string '$$', that will be dynamically
-replaced with the identifier from that column.
+This optional setting specifies remote URLs for linking out to those resources.  When
+it is set, the names in the columns from the metadata TSV file whose field names match
+this setting will be turned into hyperlinks to the corresponding resources.  If a URL
+includes the string '$$', it will be dynamically replaced with the identifier from that column.
  </p>
 <p>Example:
 <pre>
-subtrackUrl https://www.ncbi.nlm.nih.gov/sra/$$
+subtrackUrls accession=https://www.ncbi.nlm.nih.gov/sra/$$ project=https://www.ncbi.nlm.nih.gov/bioproject/$$
 </pre>
 </p>
 </div>
 
 <DIV class="faceted_example1"><span class="types view"></span>
 <div class="format"><B>Example of a faceted composite track containing different track types:</B></div>
     <pre>
     track facetedExample
     shortLabel Facet example
     longLabel Example of a faceted composite with subtracks
     type bed3
     metaDataUrl https://server.com/path/to/metadata.tsv
     primaryKey accession
     compositeTrack faceted