May be insignificant, but I really like reading all the relay messages in the book and this detail caught my curiosity.

I wonder what 'SjK' stands for. It's found in all the relay messages, in the Language path section. For example:

Language path: Firetongue->Cloudmark->Triskweline, SjK units [Firetongue and Cloudmark are High Beyond trade languages. Only core meaning is rendered by this translation.]


Language path: Samnorsk, SjK: Relay units

Is it an abbreviation for something like 'translating software used'? That's my current interpretation.

  • Great book... This is one of the books I keep on my shelf and re-read every few years.
    – GEdgar
    Mar 3, 2020 at 20:14

2 Answers 2


Sjandra Kei. Sjandra Kei is the "New Earth" sort of planet, the place where most of humanity lives. It is in one of faster zones of thought where faster than light flight is possible, but nowhere near The Transcendent.

There is also "The Old Earth", our own planet, 3rd rock flying around Sol star from which humanity came from. The problem is, 1) nobody now knows where "The Old Earth" is supposed to be and its location now lives only in memories and legends, sort of like Atlantis for us 2) it is in the slowness zone, where it is impossible to fly faster than the speed of light so nobody can get in and out in a lifetime to look for "Original Earth". More than one expedition was lost in an attempt to find it.

The thing you might be more familiar with is "Sjandra Kei Commercial Security Fleet" which is used as an answer in this question.

Basically, what happened is:

There were multiple calamities on Old Earth. There was age of space exploration and "Age of Broken Dreams". Age of Broken Dreams is so called because humans realized that FTL travel and artificial intelligence and some other technologies are impossible. Turns out, they are impossible because of galactic Zone they are in, which is one of Slow zones.

One offshoot of humanity finally got out of Slowness zone after untold millennia of travel and built their home on Sjandra Kei, where all those "impossible" things are actually possible. Most of humanity outside of Slowness zone is Sjandra Kei humanity. Pham Nuwen is one of exceptions.

Basically SjK units are "humanity language units", sort of like English is trade language on most of our planet now, despite there being multiple "nationalities" on Sjandra Kei with their own language (and we meet some of them in SjK Commercial Security Fleet), Sjandra Kei trade language is considered to be default human language. Also, if I understood correctly, Triskweline and Samnorsk are some of local Sjandra Kei languages.

So, basic meaning of this is:

Firetongue->Cloudmark->Triskweline, SjK units [Firetongue and Cloudmark are High Beyond trade languages. Only core meaning is rendered by this translation.]

Firetongue was translated to Cloudmark, Cloudmark was translated to French (or Norwegian, or Japanese or whatever local language you choose) written in English notation.

Like this: "なの" written as "nano" where "なの" is Triskweline and "nano" is SjK units.

And difference between SjK units and SjK Relay units: SjK units are your full language units. SjK Relay units is simplified notation made for trade and business deals. Sort of like Chinese (Traditional) and Chinese(Simplified). It's the same notation, just uses subset of full signs. And that's one of the reasons I absolutely love "Fire Upon the Deep".

  • 1
    So Triskweline and Samnorsk are two commonly used languages on Sjandra Kei, and 'SjK units' or 'SjK: Relay units' indicates the used script or encoding or something like that? Mar 2, 2020 at 7:24
  • 4
    Yes, pretty much like that. You can write "nan da kore wa" and that would be recognizable Japanese written in English notation. Or you can write it like: 何だこれは and it would still be Japanese only encoded in Japanese notation. Now replace Japanese with Triskweline and English notation with Sjandra Kei units.
    – jo1storm
    Mar 2, 2020 at 7:27

My guess for the "units" in there: these are units of measurement, like meters, grams, and seconds. Whatever units were in the original message were converted to these units, those used on Sjandra Kei. So when it says something about "kiloseconds" or "light years" or whatever, these have been converted to be understandable by SjK readers.

Vernor Vinge has a background in math and physics, so of course that usage of "units" is well-known to him.

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