6aca098fdf7765a7122271fdcc18d5ddfe468edc
max
  Sun Oct 4 09:59:09 2026 -0700
trackDb docs: maxItems now also sets the VCF record limit of vcfTabix tracks, refs #37306

diff --git src/hg/htdocs/goldenPath/help/trackDb/trackDbLibrary.shtml src/hg/htdocs/goldenPath/help/trackDb/trackDbLibrary.shtml
index 2bba21bdfcb..640b8e7d94d 100644
--- src/hg/htdocs/goldenPath/help/trackDb/trackDbLibrary.shtml
+++ src/hg/htdocs/goldenPath/help/trackDb/trackDbLibrary.shtml
@@ -2345,37 +2345,43 @@
     <code>itemRgb off</code>, or by a <code>color</code> setting when neither the track nor
     its parent says <code>itemRgb on</code>. The currently
     selected scheme is stored in the cart variable <code>&lt;trackName&gt;.colorField</code>.
     When a non-default scheme is active, the track long label gains a
     <em>(Coloring by: &lt;label&gt;)</em> suffix.
     </P>
     <P><B>Example:</B></P>
     <pre>
     colorFields default="Kozak strength" colorByEvidence="Evidence type" colorByHlaClass="HLA class"
     </pre>
     <P>This creates a three-option dropdown. <code>colorByEvidence</code> and
     <code>colorByHlaClass</code> must be extra fields in the bigBed whose values are
     <code>R,G,B</code> strings.</P>
 </DIV>
 
-<DIV class="maxItems"><span class="types bed bigBed broadPeak psl"></span>
+<DIV class="maxItems"><span class="types bed bigBed broadPeak psl vcfTabix"></span>
 <div class="format"><code>maxItems &lt;integer&gt;</code></div>
     <P>Maximum number of items to display individually in full or pack or squish mode.  When the maximum is
     exceeded, the track switches to coverage mode.
     Default: 1000. For <code>type bigBed</code> tracks, this setting can never 
     be larger than the hg.conf setting bigBedMaxItems, which by default is 100,000 at UCSC.
     </P>
+    <P>For <code>type vcfTabix</code> tracks, <code>maxItems</code> is the maximum number of
+    VCF records loaded for the current window. If the window holds more, the track asks the
+    user to zoom in. Without this setting, the limit is the hg.conf setting vcfMaxItems,
+    10,000 by default. Raising it lets the haplotype display of a large genotype VCF be
+    viewed in larger windows, but drawing becomes slow with many samples.
+    </P>
     <P>bigBedMaxItems is configured globally for a Genome Browser server and sets an upper limit
     on how many features can be loaded at most from a bigBed file, to avoid a
     single track making a Genome Browser view unusable at high zoom levels so
     it the upper limit for all maxItems settings of any tracks shown on a
     Genome Browser.  If you have feedback on these values,
     please do not hesitate to contact us.</P>
     <P><B>Example:</B>
     </P>
     <pre>   maxItems 25</pre>
 </DIV>
 
 <DIV class="maxWindowCoverage"><span class="types bed bigBed genePred bigGenePred psl bigPsl chain bigChain narrowPeak bigNarrowPeak broadPeak bam rmsk bedLogR vcf vcfTabix"></span>
 <div class="format"><code>maxWindowCoverage &lt;integer&gt;</code></div>
     <p>When too many individual bed items might be shown in the Browser image
     (such as might occur when a large region of a chromosome is viewed),