Adobe Acrobat Portable Document Format (.pdf)

Includes PDF Archive or PDF/A , a file format for the long-term archiving of electronic documents defined in RFC 3778. PDF/A is based on the PDF Reference Version 1.4 from Adobe Systems Inc. (implemented in Adobe Acrobat 5) and is defined by ISO 19005-1:2005, an ISO Standard that was published on October 1, 2005. PDF/A is in fact a subset of PDF, obtained by leaving out PDF features not suited to long-term archiving. This is similar to the definition of the PDF/X subset for the printing and graphic arts. For more detail see the Wikipedia article Portable Document Format.