PDF/VT
A variant of PDF/X that can include variable data, which is particularly useful for digital printers where every copy can be different. PDF/VT-1 can contain lists of variable information internally, while PDF/VT-2 (so far not released) will be able to reference external databases, allowing the same file to print different content. As with other PDF variants, this is now an ISO standard (ISO 16612-2), with development by committee.