An xlts file extension is related to data files used by Umbraco PRO CMS system.
XLTS file extension - Umbraco PRO data
What is xlts file? How to open xlts files?
File type specification:
The xlts file extension is associated with the Umbraco PRO a some kind of content management system, which enables users to create and manage content for web pages.
The xlts file contains some kind of data used by Umbraco PRO.
This xlts file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.