The Art and Rare Materials BIBFRAME Extension (ARM), first published in 2018 as part of the Andrew W. Mellon Foundation-funded Linked Data for Production (LD4P) project (2016-2018), is currently undergoing its second revision cycle. It has grown in scope to cover four distinct and interrelated domains; in its current form it seeks to extend the BIBFRAME ontology with additional classes and properties to describe Art, Rare Books, Archives, and Manuscripts. The current revision task force, under the joint auspices of the Society of American Archivists (SAA) and the Rare Books and Manuscripts Section (RBMS), is now in the second year of its two-year work cycle. This presentation will provide an update on the work to date, with brief reports from each of the four subject domains as well as current considerations for the overall direction of the extension, technical upgrades, and integrated approaches to ontology development.