http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Using master slides and master styles for a consistent design in PowerPoint 2016
Master slides are what you want when you want to apply formatting across many slides; they save you the trouble of formattting slides one at a time. This video explains how to update formatting or a theme on a master slide, fix the layout in Slide Master view, and designate a master style.
Title from resource description page (viewed May 21, 2018).