First, "bt2016" might stand for something. "BT" could be a company abbreviation; British Telecom is often abbreviated as BT. Then "2016" is a year. So maybe it's related to a document, project, or product from 2016.
I can also consider breaking down "ultsc". "Ult" as before, "SC" as "System Component", "Service Catalog", or "Special Configuration". Maybe it's a model number for a server, router, or some hardware. If it's related to networking equipment, British Telecom often uses specific nomenclature for their products and projects. bt2016r73146ultsc
Next, "r73146" – "r" is commonly used as a prefix for revision numbers. So "r73146" would be revision 73146. That makes sense in technical contexts where documents or products have multiple revisions. First, "bt2016" might stand for something