Costello (surname) to a Gaelic translation of Jocelyn, Jocelyn d'Angulo's given name. In fact, MacOisdealbhaigh is the Gaelic translation of his brother Hostilo (or Hostilio) d'Angulo's first name. Oisdealbh is a much more obvious translation of Hostilo. It is Hostilo's descendants who would bear the surname Mac Oisdealbhaigh (son of Oisdealbh or Hostilo). The surname would later be anglicized to Costello, Costelloe, and Costellow. Gilbert d'Angulo is also sometimes listed as the son of Jocelyn d'Angulo in error. Gilbert d'Angulo is the father of both Jocelyn and Hostilo. It occasionally has been adopted as a pseudonym or stage name by famous people
Mac and Mc together example has been taken as representative of a possible paradigm. A book on filing rules from 1918 gives an example showing Mc and M' treated as abbreviations, i.e. for Mac, and ordered as if in the expanded version; and a similar book from 1922 makes the rule one of a number that apply also to St. (Saint) and Mrs. (Mistress). A 1938 book that is a comparative study of cataloguing in various British libraries regarded Mac + Mc + M' sorting as an example of achieved "standardisation" in alphabetisation. It gave further examples where, it argued, such standardisation would be