The PDF specification has gone through multiple versions since its first version was published in 1993. Each release has added new features. All non-deprecated features in a PDF version are also included in subsequent versions. A PDF file includes a header identifying the PDF version to which it conforms. A PDF reader will attempt to read any PDF file, even if the file’s version is more recent than the version that the reader implements.
Table 1. PDF specification versions
| Version | Year | Acrobat Reader version |
|---|---|---|
| 1.3 | 2000 | 4.0 |
| 1.4 | 2001 | 5.0 |
| 1.5 | 2003 | 6.0 |
| 1.6 | 2004 | 7.0 |
| 1.7 | 2008 | 8 |
| 2.0 | 2017 | – |
There are also specialized subsets of PDF that have been standardized by ISO. Some of these have multiple versions that are each based on a specific PDF version.[5]
PDF/X : “PDF for Exchange”.
PDF/A : “PDF for Archiving”.
PDF/E : “PDF for Engineering”.
PDF/VT : “PDF for exchange of variable data and transactional (VT) printing”.
PDF/UA : “PDF for Universal Accessibility”.