ISDU System and Object Naming Convention

The System and Object Naming Convention (SONC) is a system used for naming star systems and the astronomical objects within them. This convention was devized by the Integalactic Scouts Data Union (ISDU) for the easy, unambigous (and ideally intuitive) naming of astronomical objects.

Systems

The official designation of a system as determined by the ISDU System and Planet Naming Convention is is as follows: Galaxy, Sector Subsector Hex
The official designation for the Sol system for example is:
Milky Way, Nearspace F 0101
(Milky Way is the galaxy, Nearspace is the sector, F the subsector, and 0101 is the hex number)
There is no strict system for the naming of galaxies. Instead, a publically available list of officially recognized names is maintained by the ISDU. The Milky Way and the Antiqua galaxies are currently the most significant galaxies, as these are the origin galaxies for all known life thus far.
Similar to galaxies, there is no strict system for the naming of sectors; a publically available list of officially recognized names is maintained by the ISDU. An example of a sector is the Cunaba sector.
Subsectors are designated a letter A to P, spinward to trailing, coreward to rimward.
Finally, the hex number is simply the four digit number of the hex the system is assigned to.
All this together provides a relative position of the system's location within a known galaxy. However, due to the relatively arbitray naming of galaxies and (especially) sectors, ISDU system names are not perfectly intuitive or uniform. The same system can be represented in a wide variety of ways depending on which galaxy and sector names a writer chooses to use. The ISDU does provide coorilated galaxy and sector names, but does not mandate that coorilated names be used (i.e. one can refer to the Antiqua galaxy by its name in one language, and refer the the Cunabula sector by its name in an entirely unrelated language when refering to a specific system within those locaitons and this would be acceptable).

Important Terms for the Naming of Objects

Hierarchies

Hierarchies are how the objects within a system are divided based on what other objects they orbit. In the SONC, there are three levels of Hierarchy: First, Secondary, and Tertiary. These are defined later, bust put simply; Objects in the First Hierarchy do not orbit any objects within the system except other First Hierarchy objects, Secondary Hierarchy objects orbit First Hierarchy objects, and Tertiary Hierarchy objects orbit Secondary Hierarchy or Tertiary Hierarchy objects.

Designators

Designators are characters used to represent objects in a system. Objects are assigned designators depending on their Hierarchy. An objects official name under the SONC consists of the System name followed by the designator of any objects the object orbits in descending hierarchical order followed by the designator of the object itself.

Sets and Companions

Sets are any number of objects (regardless of Hierarchy) which an object orbits. A set is denoted by concatenating all the designators of set members with the plus symbol “+”.
Companions are members of a special kind of set called a Companionship. A companionship is any number of objects within the same Hierarchy that are gravitationally bound to and in orbit around each other. Companionships are distinct from typical sets in that members of a set can be of any hierarchy and may or may not interact with one another, whereas companions must be within the same hierarchy and directly interact with each other.
In some respects, companion objects may act as a single object. When denoting a Companionship, the designators of all companions should be place in parentheses “()”. For objects designated by numerals, a comma “,” should be used to separate the designators.

The First Hierarchy

The First Hierarchy of a system is where most stars and other similar massive stellar objects, such as black holes and pulsars, are found. Objects in the First Hierarchy are defined as “Any object which does not orbit any other object within the system except other First Hierarchy objects”.
Under the SONC, First Hierarchy objects within a system are given a designator in the form of a capital Latin letter which is appended to the system name. These are, in order: A B C D E F G H J K L M N P Q R S T U V W X Y Z Note:

• The letter I has been omitted to prevent confusion with lowercase L (l) or the numeral for one (1).
• The letter O has been omitted to prevent confusion with the numeral 0.

The following rules are used when assigning designators to First Hierarchy objects in a system:

• The first letter assigned will be A, followed by B, then C, and so on.
• Once the letter Z has been assigned, additional letters will be assigned to the next object, AA, followed by AB, AC, and so on.
• Stars are to be assigned letters first, in order of brightest to dimmest.
• Pulsars are to be assigned letters next, in order of most to least massive.
• Black holes are to be assigned letters next, in order of most to least massive.
• All other objects are to then to be assigned letters from most to least massive.

The following steps are followed to assign each First Hierarchy object its designator:

1. The first object is assigned A.
2. The next object is assigned B, and so on, except in the event that the first object has one or more companions.
3. Should the first object have one or more companions, the first companion will instead be assigned B, and additional companions will be assigned C and so on.
4. After all companions of the previous object are assigned letters, the next object (which is not a companion of the previous object) is to be assigned the next available designator.
5. Should the next object have any companions, the next available letter should be assigned to its first companion, followed by its next companion and so on until all companions are assigned a designator.
6. Steps 4 and 5 are to be repeated until all objects in the First Hierarchy are assigned a designator.

Secondary Hierarchies

Secondary Hierarchies are where most planets and similar astronomical objects are found. Objects in a Secondary Hierarchy are defined as “Objects which orbit the same First Hierarchy object or set of First Hierarchy objects exclusively and which are not First Hierarchy objects themselves”.
It should be noted that while there is only ever one First Hierarchy in a system, there can be several Secondary Hierarchies.
Objects within a Secondary Hierarchy are assigned numbers as designators.
The following rules are used when assigning designators for Secondary Hierarchy objects in a system:

• Objects within a Second Hierarchy are to be numbered in order of discovery, with the first object discovered in a set being 1, followed by the second discovered in the set being 2, and so on.
• Should multiple objects in the same Secondary Hierarchy be discovered simultaneously, they are to be numbered in order of closest proximity to the object they orbit or, should they orbit a First Hierarchy set, closest proximity to the Barycenter of their First Hierarchy set, starting from the lowest available number within that Secondary Hierarchy.

Notes: ]Due to advancements in the methods of object discovery, the second rule is often unnecessary, as all objects are discovered nearly simultaneously.

Tertiary Hierarchies

Moons and other natural satellites fall into the Tertiary Hierarchy. Objects in the Tertiary Hierarchy are defined as “Objects which orbit Secondary Hierarchy objects regardless of whether they orbit objects of other hierarchies as well”.
Under the SONC, Tertiary Hierarchy objects within a system are given a designator in the form of a lowercase Latin letter. These are, in order: a b c d e f g h j k l m n p q r s t u v w x y z Note:

• The letter i has been omitted to prevent confusion with lowercase J (j).
• The letter o has been omitted to prevent confusion with the numeral 0.

The rules for Tertiary Hierarchy object designator assignment is as follows:

• Objects within a Second Hierarchy are to be assigned letters in order of discovery, with the first object discovered in a set being a, followed by the second discovered in the set being b, and so on.
• Should multiple objects in the same Secondary Hierarchy be discovered simultaneously, they are to be assigned letters in order of closest proximity to the object they orbit or, should they orbit a Secondary Hierarchy set, closest proximity to the Barycenter of their Secondary Hierarchy set, starting from the lowest available number within that Tertiary Hierarchy.

Objects which orbit Tertiary Hierarchy objects are still defined as Tertiary objects, though they should be treated as though they are of a lower Hierarchy for the purposes of appending their designator onto the name of the object or set they orbit.