I'm playing with Gaia DR2 catalog, which I downloaded along with distances estimation for 1.3B entries. I was looking for a way to locate stellar objects anywhere in the Galaxy without having pure coordinates. I decided to create a localization system similar to Plus-Code but allowing to identify any 1x1x1 pc region of the galaxy. Each of these block being divisible further in 0.00005 ly segments. An example of a complete GPC (Galactic Plus Code) would be 2N.433.7HM.R75.36J+8888.8222.3FFF
You can get more details at : OneDrive Hosted Excel File
A bit of an early draft. Comments are more than welcome.