Boguen noted that the card indexes are generally more accurate than the tombstones themselves. People sometimes were buried in family plots without an accompanying memorial. Some headstones have deteriorated or disappeared completely. In other cases, a headstone may have been placed in the cemetery "in memory of" someone who had a connection to Belfast but is not actually buried here.
The records can be viewed on the city's website at http://cemetery.cityofbelfast.org/. The database can be searched by first name, last name or burial year and includes a map that highlights the section of the cemetery in which the person is buried.
You can read more in an article by Ethan Andrews in the Penobscot Bay Pilot at http://goo.gl/GOQ8y.
My thanks to newsletter reader Sallee Garner for telling me about this great resource.