The most important record source, the mid-19th century survey of Ireland known as Griffith's Valuation, is organized by poor law union, parish, barony, and county. But wills probated before 1858 are organized by diocese, and after 1858 by probate district; while parish registers, marriage license bonds, and census records all have an organization linked to one or another of these administrative divisions. To help in identifying the precise location...