The ISO standard PDF/A-1 was published in 2005 with the aim of specifically narrowing the functional scope of PDF so that standard-compliant files are suitable for long-term archiving. At that time, PDF was still defined by the Adobe Reference. However, PDF/A was not intended to create a new PDF Reference. Instead, the existing PDF reference was “downsized”. In 2011, the second part of the standard was published: PDF/A-2. The most important innovation was certainly the fact that this part of the standard could now be based on PDF as an ISO standard, ISO 32000-1 (corresponds to PDF 1.7). The implicit XMP definition from Adobe had also become an ISO standard in the meantime. The further development of the PDF format also allowed newer functions to be approved for PDF/A. These include, for example, OpenType fonts, JPEG2000 image compression, and newer comment types. In 2013 the 3rd part of the standard appeared: PDF/A-3. The only innovation here is the possibility of embedding any files. All that needs to be done is to mark how the embedded files relate to the envelope PDF/A-3: Previous version or other representation.