Tens of thousands of years ago the citizens of Earth built great slow moving 'sleep ships' that were capable of reaching distant stars while their crew spent centuries in cryopreservation. Millions of humans left Earth in a great exodus that lasted hundreds of year. Then the exodus stopped. The period of Earth history directly after the exodus is referred to as "As the Blank Ages", because we have no clear history of that time.
During the Blank Ages, the humans of new worlds struggled on in isolation. Some of those new worlds thrived. A organization called the FTO came out of some of those colonies. The FTO's interstellar ships moved almost as fast as light. They found other colonies. For thousands of years the FTO connected the many human worlds through education, trade and aide. They never found Earth. Earth found them.
The people of Earth had developed a technology commonly called a Jump-drive. It is an interstellar 'engine' that allows spaceships to travel lightyears in literally no time at all. The government of Earth, called the Dynasty, set out to "find, unify and elevate all elements of humanity".
Star Systems: Convention holds that populated Star Systems are named after the populated planet or the planetary body with the largest population. Non-populated star systems are named after the star.
Sub-Sectors and FTO’s Galactic Cartography: The FTO was humanity’s first true interstellar organization. The FTO trade ships, traveling at 0.999% of light speed, spent centuries linking the many human colonies. They created a rough system for mapping the galaxy. The concept of sectors was developed. The concept of sectors was not based on mapping, but based on theory generated from astronomical observations of galactic movement and matter distribution. All of human occupied space, or known space exists within a single sector as defined the by the FTO’s system.
The known galaxy was divided into sub-sectors. Theoretically, a sub-sector would extend 200 parsecs core to rimward (from the center of the galaxy towards the rim) and 200 parsecs spinward. Thus, a sub-sector would be a trapezoid. All navigable points in the z-plane within that region would be part of that sub-sector. They named the sub sectors after ancient Earth myths regarding small totems or icons often call zodiacs. For example, Rabbit sub-sector is a region of the galaxy that is several sub-sectors rimward of the Earth System. The sector extends 192 parsecs from its most core-ward mapped star to its most rim-ward mapped star system. Rabbit Sector extends 153.6 parsec from its most anti-spin mapped point to its most spin-ward mapped point.
Navigational Grids, The Dynastic Migration and the Galactic Scouting Guild (GSG) : The Dynasty developed the interstellar jump drive (D-drive). The D-drive allows a spacecraft to instantaneously jump from one point in space to another (The physicists claim the craft doesn’t actually move, but rather space is folded so that craft occupies two points at once. The energy requirements for making a Jump are enormous.) Jumping can also be dangerous. Jumping too close to a gravity well or hazard is one danger, but more concerning is the possibility of getting lost. If the craft jumps too far from a star or a concentrated source of matter it may not be able to recharge the D-drive in a timely manner. Efficient and safe navigation is made possible by the Galactic Scouting Guild’s (GSG) Navigation Grid system. The GSG makes detailed measurements of navigable phenomenon (usually a Star System) and places them into a Navigation Grid.
The Navigational Grid is actually a sophisticated mathematical model that takes into account the temporal and spatial changes that occur during interstellar travel. The visual output of the Grid uses the FTO sector system and then applies 2-D matrix to the sector. The most anti-spin and core-ward point in the sector is designated A1-prime. The agency making the Grid then attempts to map another location less than 9.6 parsecs (9.6 is average distance travelled by a jump drive). If that location is spin-ward of A1 it will be designated A2-prime. If it is rim-ward it will be B1-prime. Sometime multiples points will be less than 9.6 parsecs from navigable point. These receive “ancillary designations (eg B1-second, B1-tert, B1-quat, B1-quin and so on). Navigational Grids actually contain a lot more information than the simplistic 2D grid model relays. A reliable Grid will only contain points that have been carefully mapped. A reliably safe jump can not be calculated by simply observing a star astronomically from light years away. The GSG, the most rigorous and thorough mapping originization will not add a point to a grid till the system or navigable object has been fully mapped, weighed (total mass calculated) and observed for an extended period of time.
The Dynasty, the FTO, the Union of Worlds and the GSG all maintain slightly different standard Navigation Grids (It is assumed that non-human factions must have similar systems). The GSG has the most developed grids and a major source of revenue for the GSG is selling of Navigational Information to the other factions. The most popular and most complete Navigation Grid is the Galactic Scouting Almanac. This program is continually updated by the GSG. The Galactic Scouting Almanac not only provides a Navigational Grid, but provides detailed entries on many of the mapped points. Most Sector Grids are far from complete. Despite their being thousands of stars in Rabbit sub-sector, only 57 have mapped in the Galactic Scouting Almanac at this writing. The anti-spin and rim-ward quadrant of Rabbit sub-sector is entirely unmapped. Of course there are Rouge Grids, Scouting Grids and Speculative Grids. These are Grids that don't meet the standards of the FTO, GSG or Dynasty, but can still be used for Navigation. Indeed the Galactic Scouting Guild depends on the use of Scouting Grids to reach 'unmapped' systems. Navigation by these sub-standard, though sometimes necessary, grids is just riskier.