- PDF/X
Known as PDF for Exchange, these seven standards dictate graphics exchange to standardize the use of PDF for transferring graphic arts content files between sites, publishers, and printers. - PDF/A
For most documents, PDF is usually all you need to enable everyday readability and sharing. If you need to ensure those documents are readable over the long-term, however, PDF/A should be your choice in your PDF software. - PDF/E
This compliance standard is designed for documents used in geospatial, construction, and manufacturing workflows to provide an easy, and consistent, exchange of engineering and technical documents. The goal of this compliance standard was to reduce the costs associated with storage and exchange of paper documentation.
HTML vs PDF...
Open vs protected, fluid vs structured...