SIMBAD query result

Please have a look at the "Dictionary of Nomenclature"

Result of query: info cati NGC 2957B

.

 [Class]      Acronym  (Explanation)   . . . . . . . . . in Simbad, use:
 [?]          N (Abbreviation of NGC)  . . . . . . . =E= NGC NNNNA
 [?]          NGC (New General Catalog)  . . . . . . =E= NGC NNNN
                                                      or NGC NNNNA
                                                      or NGC NNNNAA        (L)
 [?]          RNGC (Revised New General Catalog) . . =E= NGC NNNNA
=E= indicates catalogues available in electronic form at CDS
(L) following the Usage indicates a 'format' found later in the literature,
    which is not recognized by SIMBAD.