PDF/A-2
PDF/A-2 describes the usage of PDF documents for long term archiving of electronic documents based on PDF version 1.7. ISO standard ISO 19005-2:2011 determines the requirements a PDF document must fulfill in order to be regarded as a standard compliant PDF/A-2 document. PDF/A-1 documents remain valid; PDF/A-1 compliant data also satisfy the requirements of the respective PDF/A-2 conformance level.