Office Open XML file formats: Difference between revisions

Revision as of 03:11, 18 November 2010

Revision as of 20:14, 20 January 2011

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Some have queried the need for Office MathML (OMML) instead advocating the use of [[MathML]], a [[World Wide Web Consortium|W3C]] recommendation for the "inclusion of mathematical expressions in Web pages" and "machine to machine communication".<ref>{{cite web| url=http://www.zdnet.com.au/news/software/soa/Microsoft-Office-dumped-by-Science-and-Nature/0,130061733,339278690,00.htm| title=Microsoft Office dumped by Science and Nature| publisher=ZDNet Australia| date=18 June 2007}}</ref>

=== DrawingML ===<!-- [[English Metric Unit]] links to here -->

[[Image:DrawingML example.png|220px|thumb|right|Example of DrawingML charts]]

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DrawingML is unrelated to the other [[vector graphics]] formats such as [[SVG]]. These can be converted to DrawingML to include natively in an Office Open XML document. This is a different approach to that of the [[OpenDocument]] format, which uses a subset of SVG, and includes vector graphics as separate files.

A DrawingML graphic's dimensions are specified in [[English Metric Unit]]sUnits (EMUs). It is so called because it allows an exact common representation of dimensions originally in either English or Metric units. This unit is defined as 1/360,000 of a [[centimeter]] and thus there are 914,400 EMUs per [[inch]], and 12,700 EMUs per [[point (typography)|point]]. This unit was chosen so that integers can be used to accurately represent most dimensions encountered in a document. Floating point cannot accurately represent a fraction that is not a sum of powers of two and the error is magnified when the fractions are added together many times, resulting in misalignment. As an inch is exactly 2.54 centimeters, or 127/50, 1/127&nbsp;inch is an integer multiple of a power-of-ten fraction of the meter (2×10⁻⁴&nbsp;m). To accurately represent (with an integer) 1&nbsp;μm = 10⁻⁶&nbsp;m, a divisor of 100 is further needed. To accurately represent the [[point (typography)|point]] unit, a divisor of 72 is needed, which also allows divisions by 2, 3, 4, 6, 8, 9, 12, 18, 24, and 36 to be accurate. Multiplying these together gives 127×72×100 = 914,400 units per inch; this also allows exact representations of multiples of 1/100 & 1/32&nbsp;inch. According to [[Rick Jelliffe]], programmer and standards activist (ISO, W3C, IETF), EMUs are a rational solution to a particular set of design criteria.<ref>{{ cite web|date=April 16, 2007 |author= Rick Jelliffe in Technical | url = http://www.oreillynet.com/xml/blog/2007/04/what_is_an_emu.html | title = Why EMUs? - O'Reilly XML Blog | publisher = Oreillynet.com | date = 2007-04-16 | accessdate = 2009-05-19}}</ref>

Some have criticised the use of DrawingML (and the transitional-use-only [[Vector Markup Language|VML]]) instead of [[World Wide Web Consortium|W3C]] recommendation [[SVG]].<ref>{{ cite web | url=http://reddevnews.com/features/article.aspx?editorialsid=2356 | title= The X Factor | publisher=reddevnews.com |month=October | year=2007 }}</ref> VML did not become a W3C recommendation.<ref>{{ cite web | url = http://www.w3.org/TR/NOTE-VML | title = VML&nbsp;— the Vector Markup Language | publisher = W3.org | date = 1998-05-13 | accessdate = 2009-05-19 }}</ref>