How to create PDF/A from a regular PDF?
You will need to use Acrobat Pro if you do not have this program; don't worry, the library has the software available. Acrobat Pro is available on the Macs in the DSL and at the microfilm station on the first floor.
Open up Acrobat Pro DC from the Finder by clicking on Go > Applications > Acrobat Acrobat DC (or open the program from the desktop of the PC)
After you close Acrobat Pro, you can open the details on the file and it should list Attributes: A