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Notes (2018)[edit]

Mains & Branches[edit]

Star systems on long (51 or more stars) mains. Frequently are separated into arms or branches for identification purposes.

Prominent examples include:

Traces & Clusters[edit]

Star systems on smaller (5 - 50 stars) groupings. Most of these astrographic features are located in just one or two subsectors.

Traces & Clusters:


Origin of the terms (2016)[edit]

The first use of "Main" I've been able to find is in Library Data (N-Z) from 1983, in a reference to the Spinward Main.

The term Cluster shows up in the The Spinward Marches (referring to the Jewell cluster). And again in Library Data (A-M) under Glea (Glean Cluster, an unusually rich grouping of 16 Hiver-habitable worlds, mutually accessible by jump-I shipping). Library Data (N-Z) notes under Subsector that a synonym is "cluster", giving an approximate upper size on the term.

Later books (and non-canon references) make similar kinds of off-hand references to the terms "Main", "Branch", "Cluster", and "Trace". That is, the terms are used in names, like "Spinward Main" without any precise definition.

Based upon the existing known names and some of the references, I applied the separation at 50 system to distinguish between a Main (with branches) and a Trace or Cluster. As the latter two terms are never defined (just used), the wiki asserts they are interchangeable.

Since the smallest grouping of independent systems given a name in canon was between five and 10 systems, I asserted the smallest grouping was 5 systems. The list above gathered from the COTI group-mind may provide a non-canon version of a name for the smaller groupings.

- Tjoneslo (talk) 18:36, 19 July 2016 (EDT)

Hi Thomas, I think we should change it to 2 to 50 then for the cluster/trace and 51+ for the main. What sayeth you?

  • BTW, thanks for the research. It confirms my findings.
  • Maksim-Smelchak (talk) 19:46, 19 July 2016 (EDT)

Do you have an example of any group of size 2 to 4 given any sort of name? Canon sources are best? I picked that 5 because that was smaller than the smallest named grouping I can find. Tjoneslo (talk) 20:17, 19 July 2016 (EDT)

I'll see if I can find some.
- Maksim-Smelchak (talk) 22:04, 19 July 2016 (EDT)

As I was going through the process of getting the Empty Quarter into the Wiki, I arbitrarily picked four for a cluster and 30+ for a main.

- Ssteve

There still is no definition for any of these astrographic features.

  • So that works in the absence of definition.
Technically a cluster or trace is two or more.
Mains have no hard definition, bit would require a minimum of two stars. Hard to say.
- Maksim-Smelchak (talk) 13:14, 4 January 2018 (EST)
Just to add to the confusion. The Traveller Map Mains overlay defines three sizes of "Mains" you can highlight: small (6-10 worlds), medium (11-50 worlds) and large (51+ worlds). Tjoneslo (talk) 19:58, 4 January 2018 (EST)

Discussions (2015)[edit]

CotI Link: What does one call a J-2 jump "main"?

Notes (2015)[edit]

Collected ideas from CotI members:

  • Access
  • Arm
  • Backwater
  • Branch
  • Bridge
  • Circuit
  • Cluster
  • Connector
  • Corridor
  • Diagonal
  • Expanse
  • Gossamer
  • Group
  • Hinters
  • Knot
  • Line
  • Link
  • Loop
  • Nexus
  • Outlet
  • Path
  • Pendant
  • Range
  • Reach
  • Route
  • Run
  • Scatters
  • Space Lane
  • Spur
  • Spread
  • Starlane
  • Stream
  • Sweep
  • Tangle
  • Trace
  • Tract
  • Trade Route
  • Whorl
  • Wisp

Greater Mains (Yellow)

  • Star systems on long (50 or more stars) mains.
  • Most multi-sector and single-sector mains are greater mains.
  • High economic and trade activity (interstellar traffic).

Lesser Mains (Blue)

  • Star systems on short (10 - 50 stars) mains.
  • Many subsector mains are lesser mains.
  • Moderate economic and trade activity (interstellar traffic).

Arms, Branches, Traces, Clusters & Others (Green)

  • Star systems with few if any significant connections to any main.
  • May be subsets of larger mains.
  • Most of these astrographic features are located in just one or two subsectors.
  • Low economic and trade activity (interstellar traffic).

Notes (2009)[edit]

If the various ship design systems are anywhere near accurate reflections of how ships are constructed in the OTU, mains have very little actual economic significance once jump-2 has been invented. For any distance greater than one parsec, Jump-2 and Jump-3 shipping is cheaper than jump-1 (A jump-2 ship costs more and carries less than a jump-1 ship of the same size, but it delivers two loads of cargo/passengers every time the jump-1 ship delivers one). The importance of mains may just be an 'urban myth' among the 99.999% of people who have no idea about the realities of star travel.

  • Rancke 23:08, 6 June 2009 (UTC)
It probably depends upon how much you believe the Type A free trader represents the true nature of the manner of trade in the Imperium. Like you said, urban myth.
The nature of mains does explain the expansion of the First Imperium (see Vilani Main, Antares Main, and the Lishun-Menden Main, and a few more to rimward.
Still, it was a cool map to make.
Actually, 'two deliveries in the same time' only works if the destination is at least two parsecs away. Remember, if the destination is only one parsec away both the jump-1 and the jump-2 ship still take 1 week to arrive. I would tend to think that a prosperous planet would tend to create prosperous economic colonies close to it, because of the long-term ease of trade. This would tend to make mains important as the Ri planets on it boost the economies of everything close to them. However, the random nature of Traveller world generation denies that this effect really exists. ~_^ --
  • Rindis 20:08, 13 August 2009 (UTC)