Admittedly, as soon as payday rolls around I'm going to have to buy some books and start studying in earnest so I won't have to ask so many basic questions. Until then, please bear with me. Having learned yesterday about the Mac/Ni prefix to surnames got me wondering about those of the O' names. Does the use of O' refer not so much to direct parentage but clan/family membership?

Ó means grandson of
Roibeard Ó Duibhir - Robert, grandson of Duibhir
Uí would probably be used for clans, i.e. Uí Duibhir - sons of Duibhir

Ceartucháin failte

But these days surnames dont change which is a pity, but far easier for admin. Though it would be far cooler, just thinking of the russian system.....
A thought, with "Ní" and "Nic". Is that used in offical documentation (ie Áine Nic Eoin) or is Áine Mac Eoin used??
Sláinte
Colm.
Ierne - Caite Éireann