Question: The Xar file format is the fully specified vector graphics file format of  UK-based software company founded in what year?

Context paragraphs:
ShrinkIt: NuFX archive is an archive file format that supports lossless data compression that is given the file extension ". SHK".  A NuFX archive or . SHK file may contain one or more files or directories and with the extension . SDK even contains entire floppy disk images.  This format actually specified via the NuFX file format, was meant to replace and "Binary II" format back in the 1980s which had the . BNY or . BQY extensions... file envelopes with no compression.  The . SHK file format permits a number of compression algorithms.  This format was originally created in 1980s by Andy E. Nicholas and was first implemented within his ShrinkIt utility.

DMPL: Digital Microprocessor Plotter Language (DMPL) is a vector graphics file format from Houston Instruments developed to control pen plotters and later used on cutting plotters.

EULUMDAT: EULUMDAT is a data file format used for specification of photometric data especially intensity distributions from light sources such as lamps and luminaries.  The file extension is . ldt.  The format was proposed by Axel Stockmar (Light Consult Inc., Berlin) in 1990.  The format is the European equivalent to the IES file format specified in IESNA LM-63.  The data in an EULUMDAT file is usually measured using a goniophotometer.  The IES file format is more formally specified and many measuring instruments

BMP file format: The BMP file format, also known as bitmap image file or device independent bitmap (DIB) file format or simply a bitmap, is a raster graphics image file format used to store bitmap digital images, independently of the display device (such as a graphics adapter), especially on Microsoft Windows and OS/2 operating systems.

FXG: Flash XML Graphics (FXG) is a specification for an XML-based graphics file format for describing two-dimensional vector graphics developed by Adobe Systems.  FXG was planned as a graphics interchange format for cross-application file support, to be used by Adobe Flash and Adobe Flash Player.

Xara: Xara is a UK-based software company founded in 1981.  It has developed software for a variety of computer platforms, in chronological order: the Acorn Atom, BBC Micro, Z88, Atari ST, Acorn Archimedes, Microsoft Windows and Linux.  It was originally called Computer Concepts, Ltd.; the company name was changed in 1995 to Xara, Ltd. and later to The Xara Group, Ltd.  On 30 January 2007, Xara was acquired by German company MAGIX AG, and now operates as a wholly owned subsidiary.

Silicon Graphics Image: Silicon Graphics Image (SGI) or the RGB file format is the native raster graphics file format for Silicon Graphics workstations.  The format was invented by Paul Haeberli.  It can be run-length encoded (RLE).  Among others FFmpeg and ImageMagick support this format.

Proprietary format: A proprietary format is a file format of a company, organization, or individual that contains data that is ordered and stored according to a particular encoding-scheme, designed by the company or organization to be secret, such that the decoding and interpretation of this stored data is only easily accomplished with particular software or hardware that the company itself has developed.  The specification of the data encoding format is not released, or underlies non-disclosure agreements.  A proprietary format can also be a file format whose encoding is in fact published, but is restricted through licences such that only the company itself or licencees may use it.  In contrast, an open format is a file format that is published and free to be used by everybody.

Metafile: Metafile is a generic term for a file format that can store multiple types of data.  This commonly includes graphics file formats.  These graphics files can contain raster, vector, and type data.  A common use for these files is to provide support for an operating system's computer graphics; e.g., Microsoft Windows uses Windows Metafile, and Mac OS X uses PDF.

Xar (graphics): The Xar file format is the fully specified vector graphics file format of Xara and Xara Photo & Graphic Designer.

Supporting paragraphs: Xar (graphics) Xara
Answer: 1981