PDF/A

Abbreviation for Portable Document Format for Archiving
A PDF format with some limited functions of PDF for the long-term archiving of documents and data.

PDF/A-1 through PDF/A-4 are standardized as ISO 19005 series.
PDF/A-1 Based on PDF 1.4, Standardized as ISO 19005-1.
PDF/A-2: Based on a PDF 1.7 (ISO 32000-1), Standardized as ISO 19005-2.
PDF/A-3: Based on a PDF 1.7 (ISO 32000-1) It allows embedding of arbitrary file formats. Standardized as ISO 19005-3.
PDF/A-4: Based on a PDF 2.0 (ISO 32000-2 ), Standardized as ISO 19005-4.