PDF Standards

PDF/X and PDF/A standards are defined by the International Organization for Standardization (ISO).

PDF/X standards apply to graphic content exchange
The most widely used standards for a print publishing workflow are several PDF/X formats: PDF/X-1a, PDF/X-3, and PDF/X-4.

PDF/A standards apply to long-term archiving of electronic documents
The most widely used standards for PDF archiving are PDF/A-1a and PDF/A-1b (for less stringent requirements).

For more information on PDF/X and PDF/A, see the ISO website.