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 dropped for some newer computer systems, and the interfiling of Mac and Mc names is an example, according to a 2006 book. There are in fact a number of options. In addition to sorting them under "Mac" and "Mc" respectively or choosing to sort them both under "Mc", it is known for Mc/Mac names to be placed in position before M. This topic has a complicated and disparate history, spread over different continents and relating to different areas of indexing, cataloguing and filing. The idea of a collating sequence itself has evolved, over time, and the "Mac and Mc" together