The files on which the News Letter today reports have been declassified in one of three places – Belfast, London or Dublin.
However, there is a growing differential between when files are being made public in the Republic and when they are released in the UK.
In the UK, the 30-year-rule has been replaced by a 20-year-rule which is being phased in, with two years of files being released each year.
Each year, that means that the gap between what is known from British files and what is known from Irish files widens.
There have been some concerns expressed south of the border that the British version of history is emerging first and that the era is being primarily understood through British eyes.
Today, the UK is releasing files from 1990, while the Republic is releasing files from 1986.
Under the current regimes in the UK and Ireland, files relating to the period of the 1998 Belfast Agreement will be released by Britain in 2021, but Dublin’s files will not be declassified for another eight years, in 2029.
From today, any member of the public can visit the Public Record Office of Northern Ireland (PRONI) in Titanic Quarter and view the original files for themselves.
The files are released based on the year in which they were closed.
That means that files which were closed in 1988 may contain documents which go back several years, or in some cases decades.