PDF/A

PDF/A is an ISO-standardized version of the Portable Document Format (PDF) specialized for the digital preservation of electronic documents.

PDF/A differs from PDF by prohibiting features ill-suited to long-term archiving, such as font linking (as opposed to font embedding).

The ISO requirements for PDF/A file viewers include color management guidelines, support for embedded fonts, and a user interface for reading embedded annotations.

Standards

PDF/A-1 is based on the PDF Reference Version 1.4 from Adobe Systems Inc. (implemented in Adobe Acrobat 5 and later versions) and is defined by ISO 19005-1:2005, an ISO Standard that was published on October 1, 2005: Document Management – Electronic document file format for long term preservation – Part 1: Use of PDF 1.4 (PDF/A-1)

PDF/A-2 is based on ISO 32000-1 – PDF 1.7 and is defined by ISO 19005-2:2011, published on June 20, 2011 under the formal name Document management – Electronic document file format for long-term preservation – Part 2: Use of ISO 32000-1 (PDF/A-2).

Portable Document Format

The Portable Document Format (PDF) is a file format used to present documents in a manner independent of application software, hardware, and operating systems. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display it. In 1991, Adobe Systems' co-founder John Warnock outlined a system called "Camelot" that developed into PDF.

Adobe Systems made the PDF specification available free of charge in 1993. PDF was a proprietary format controlled by Adobe, until it was officially released as an open standard on July 1, 2008, and published by the International Organization for Standardization as ISO 32000-1:2008, at which time control of the specification passed to an ISO Committee of volunteer industry experts. In 2008, Adobe published a Public Patent License to ISO 32000-1 granting royalty-free rights for all patents owned by Adobe that are necessary to make, use, sell, and distribute PDF compliant implementations. However, there are still some proprietary technologies defined only by Adobe, such as Adobe XML Forms Architecture and JavaScript for Acrobat, which are referenced by ISO 32000-1 as normative and indispensable for the application of the ISO 32000-1 specification. These proprietary technologies are not standardized and their specification is published only on Adobe’s website. The ISO committee is actively standardizing many of these as part of ISO 32000-2.

Palladium(II,IV) fluoride

Palladium(II,IV) fluoride, also known as palladium trifluoride, is a chemical compound of palladium and fluorine. It has the empirical formula PdF₃, but is better described as the mixed-valence compound palladium(II) hexafluoropalladate(IV), Pd^II[Pd^IVF₆] and is often written as Pd[PdF₆] or Pd₂F₆.

Synthesis

Pd[PdF₆] is the most stable product of the reaction of fluorine and metallic palladium.

Structure and properties

Pd[PdF₆] is paramagnetic and both Pd(II) and Pd(IV) occupy octahedral sites in the crystal structure. The Pd^II-F distance is 2.17 Å, whereas the Pd^IV-F distance is 1.90 Å.

See also

References

Palladium(II) fluoride

Palladium(II) fluoride, also known as palladium difluoride, is the chemical compound of palladium and fluorine with the formula PdF₂.

Synthesis

PdF₂ is prepared by refluxing palladium(II,IV) fluoride, Pd^II[Pd^IVF₆], with selenium tetrafluoride, SeF₄.

Structure and paramagnetism

Like its lighter congener nickel(II) fluoride, PdF₂ adopts a rutile-type crystal structure, containing octahedrally coordinated palladium, which has the electronic configuration t6
2g e2
g. This configuration causes PdF₂ to be paramagnetic due to two unpaired electrons, one in each e_g-symmetry orbital of palladium.

See also

References