Not to be confused with Stationary files. They don't exist, or move.
I have several, generally for different sheet sizes, or specific venues, but it is certainly easy to make that change in any one Template or Stationery file.
When you create a new document in Vectorworks you're given the choice of using a blank document or any of a number of stock (or custom) Template files. These are generally architecture based and contain many standard architectural classes.
The stock Spotlight Template contains layers for the Theatre Architecture, Soft Goods, and Scenery. The template also includes classes for Clamps, and Label Legend components.
I want more, of course. I use a lot of different classes and I store them in Stationery files. I create and set line weights in stationery files. I set all the tool preferences to my liking in stationery files. I can keep different venues in stationery files.
It's not possible to move those tool setting around easily, that kind of choice might limit the number of Templates you want to create. You can easily mass import layers and classes from one file to another in the Tools>Organization dialogue.
Of course, I discuss template files and how they might grow and change with your experience in Entertainment Design; Scenery, Lighting and Sound, with Vectorworks..., but that's no surprise.
Here's one really important reason to have a stationery file. When you create a section Viewport, Vectorworks automatically creates a class called SectionStyle. It has a really, really, really heavy outline, and a red fill. Most users will want to reference that class. If you re-define in a Template file, you only have to make that change once.
When you File>Save as Template... Vectorworks saves you template in your defaults and you can then access the template anytime you create a new file. Just write over the original anytime you want to change some of the settings.
Bit by bit, I go over some of my choices for stationery file settings.