During my screenwriting process, I have encountered something called “I/E,” which I can’t find in your glossary. What does it mean?

Mats
Gothenburg, Sweden

I/E is simply a shorthand way of writing “INT./EXT.” in a scene heading, when the action will be taking place both inside and outside of a given location, like a parked car or a garden shed. Because it’s not all that commonly used, I usually just write it out:

INT./EXT.  MINIVAN - NIGHT

Ronna knocks on the door.  A SPIKY-HAIRED GUY rolls down the window.

It’s a matter of personal preference. Many screenwriters do use I/E when the situation comes up.