What is DTG?

It's a common question: what is DTG? What does it stand for? 
The truth is... no one knows. But plenty have tried to find out. What do you think? 
Is it:

• Drag Transit Gates? These huge point-to-point dark matter terminals allow massive starships to traverse the galaxy in a fraction of the time, using less energy than traditional faster-than-light methods.
• Dimensional Tear Generators? Arcane devices capable of creating a portal, or "tear" between normal space and alternate dimensions.
• Distant Telemetry Guidance? An ancient Precursor navigation system that determines galactic position based on the galaxy's central black hole.
• The Deep Terminus Garrison? A fortress located far within the fluidic space of Al-Rem, and headquarters of the Rangers of the Deep.

Or none of the above? Is it a person, a place, a thing? A time, an era? A dark secret, or something hidden in plain sight? 
Maybe it's time to discover it for yourself...