PDF/A is an ISO 19005 standardized PDF format designed specifically for long-term digital archiving. Unlike regular PDF, PDF/A prohibits features that could compromise reliable rendering in the future: embedded JavaScript, external references, encryption, and non-embedded fonts. All resources needed for display are contained within the document itself. For your ISMS, PDF/A is relevant when archiving policies, audit reports, and evidence documents that must remain readable for many years. Define in your document control concept which documents should be archived in PDF/A format.