Office Open XML file formats: Difference between revisions

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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 Units (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 |date=October 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>