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While most star names and alphanumeric designations I've seen appear to be pure alphanumeric plus space, I have seen designations with both - and + characters in them too.

Is there a reference or standard anywhere for what characters are valid for designations and star names?

I've had a look around for this information, but I can't find any references which would allow me to write a comprehensive BNF syntax or a regular expression to parse and/or validate star names and designations.

In particular for a project I'm working researching, I would like to know if either a , comma or a | pipe character has or might ever be used in a star name or designation.

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As far as I know, there is no standard that defines valid characters for a stellar designation. Sometimes people write using Greek letters (e.g. "α Centauri") and there are many odd catalogue notations. I would not trust that star designations could not contain commas or pipes (aka vertical bar, |), although I think it would be rare.

The IAU has stated that star names are separate from the catalogue designations, and in regard to designations "it is standard practice to identify them with an alphanumeric designation. " But standard practice does not guarantee that somebody will not disregard it, and there are clearly plenty of designations already with non-alphanumeric symbols.

So, one should probably not assume too much about what characters are in the string. Presumably for safety and generality one needs to assume a Unicode string and some robust way of escaping entries.

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  • $\begingroup$ Thanks, the reason I'm interested in , and | in particular is that they are currently used as system, and comment separators respectively, and spot checking "α Centauri", it is represented by the text "Alpha Centauri", so I haven't seen any non ASCII characters used so far. $\endgroup$
    – Mark Booth
    Mar 22, 2021 at 17:15
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    $\begingroup$ simbad.u-strasbg.fr/simbad/… lists all common identifiers for Betelgeuse. Some contain a comma - common separator to distinguish components of a multiple system $\endgroup$
    – planetmaker
    Mar 22, 2021 at 18:05
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    $\begingroup$ And looking at simbad.u-strasbg.fr/simbad/… the same catalogue ommits the comma... so don't count on consistency in names $\endgroup$
    – planetmaker
    Mar 22, 2021 at 18:08
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    $\begingroup$ @MarkBooth I think this might be a bit of an XY problem in that case. If your data source uses , and | as delimiters already, then there should be no problem, or the data would be unusable. If your data source doesn't, but you want to use them, then you should just write a few lines of code to replace any possible occurence with a corresponding escape sequence. This way your program will not suddenly break if somebody decides to name a star ,|'); DROP TABLE STARS;-- $\endgroup$
    – mlk
    Mar 22, 2021 at 20:10

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