Yes, they are uniquely identifying individual flats in a block.
What will get an Eircode?
Generally all postal addresses that currently receive mail will be assigned an Eircode. For example:
Each house on a street
Each flat in an apartment block
Each house in a rural townland
Both units in a duplex unit
Factory or warehouse
Shop, hotel, bar or any business premises
Health centre, hospital or any public building
Each unit in a shopping centre
Each unit in a business park or industrial estate