Cemetery 101 Class for Family Tree University.
When I transcribe gravestones, I write down everything that is on them but I know that since gravestones are erected AFTER (well usually) the person died, the information on them is only confirming evidence and needs to be proved with vital records or other sources.
I take the death date most seriously as well as where the stone is located and what its type, style and any icons or flag holders indicate.
The person's name and how it is spelled is analyzed and if it is female (and I am lucky) the woman's maiden name. The information on birth was most likely given by someone else who signed the death record or told the gravestone artist what to write.
I have been ignoring the statement "his his/her 84th year or at 5 years, 2 months and 5 days" unless I can prove that with a birth, baptismal or even a family Bible entry.
Yesterday, I had to find out what "in the xxth year of his age really meant". So, after looking at all my books, I took the question to FaceBook. In 10 minutes I had a consensus of opinion from the genealogy community with no exceptions.
So, with that in mind, I went to the gravestone of one of my 8th great grandparents who died in Bridgewater, MA. I knew I had researched his birth, marriage and death with vital records. Then, I took this information to RootsMagic's date calculator as you can see in this screen shot.
So, in his 84th year, it meant he has celebrated his 83rd birthday and was moving toward his 84th birthday when he died.
I am glad to have made a mistake. I learned something great!