SIMBAD query result

Please have a look at the "Dictionary of Nomenclature"

Result of query: info cati ** STF 2781AB

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 [Class]      Acronym  (Explanation)   . . . . . . . . . in Simbad, use:
 [**]         ** (Double Star) . . . . . . . . . . . . . ** AAA NNNNAA
                                                      or ** AAAA NNNAA
                                                      or ** {H N} NNNAA
                                                      or ** {H} N NNNAA