All the objects in the database, galaxies, stars, clusters, ..., are indexed with their pgc number. Historically, the pgc numbering was created to unify the names of the galaxies when the database project started in 1983. ... Still, all the objects in the database (about 5 millions) have a pgc number which is used as a unique identification across the different tables. This number should not be used to build a name , since it would not be recognized by any database, including HyperLeda. ...