The faceted composite interface on the ENCODE4 DNase/ATAC/Histone/CTCF (Indiv.) track. Facets on the left filter the 6,353 subtracks, and the table lists those that match.
We are pleased to announce faceted composites, a new -interface for composite tracks that hold very large numbers of subtracks. The standard -composite works well for somewhere between 20 and 50 subtracks, but it becomes unwieldy -once the count runs into the hundreds to thousands. A faceted composite is an alternative -display for those cases: facets along the left side filter the collection while a -paginated table on the right lists the subtracks that match, letting users narrow -thousands of entries down to the handful relevant to their work. The individual-experiment -tracks in the ENCODE4 Regulation collection, announced in July 2026, -already use this interface. Faceted composites are configured entirely through trackDb -settings, so any hub developer can build one. +interface for composite tracks that hold very large numbers of subtracks. The standard composite +works well for about 20 to 50 subtracks, but it becomes unwieldy once the count reaches the +hundreds or thousands. A faceted composite is an alternative display for those cases: facets along +the left side filter the collection, while a paginated table on the right lists the matching +subtracks, letting users narrow thousands of entries down to the handful relevant to their work. +The individual-experiment tracks in the ENCODE4 Regulation collection, +announced in July 2026, already use this interface. Faceted composites are +configured entirely through trackDb settings, so any hub developer can build one.
The faceted composite interface on the ENCODE4 DNase/ATAC/Histone/CTCF (Indiv.) track. Facets on the left filter the 6,353 subtracks, and the table lists those that match.
A faceted composite otherwise behaves like an ordinary composite, with two differences:
Two optional settings extend the interface:
dataTypes – groups several files per sample, so a single row of
the subtrack table can turn on a signal track and a peak track togethersubtrackUrls – turns metadata values into links, which is useful
for accession numbers or protocol identifiersOur new Faceted Composite Tracks documentation page walks through building one, with an example hub that can be loaded directly into the browser. The complete -reference for each setting lives in our +target="_blank">example hub you can load directly in the browser. The complete reference for +each setting lives in our trackDb -documentation, and our Hub -Basics page is a good starting point if you are new to building hubs. +documentation, and our Hub Basics page +is a good starting point if you are new to building hubs.
We would like to thank Andrew Smith at the University of Southern California, who contributed the original implementation of this interface, and Jonathan Casper, who developed it into the version released at the UCSC Genome Browser. We also thank Lou Nassar, Gerardo Perez, Clay Fischer, Brian Raney, Max Haeussler, and Jairo Navarro for testing, feedback, and documentation.
We are pleased to announce the release of two new proteome-wide missense variant effect prediction tracks for hg38: