.DOCX File Format – Styles

Office Open XML Document

Named formatting lives in word/styles.xml, reached by the main document’s styles relationship. A paragraph or run points to a style by its ID, and the text carries only what differs from the style.

An example

<w:styles xmlns:w="…">
  <w:docDefaults>
    <w:rPrDefault><w:rPr>
      <w:rFonts w:ascii="Calibri" w:hAnsi="Calibri"/>
      <w:sz w:val="22"/>
    </w:rPr></w:rPrDefault>
    <w:pPrDefault><w:pPr>
      <w:spacing w:after="160" w:line="259" w:lineRule="auto"/>
    </w:pPr></w:pPrDefault>
  </w:docDefaults>
  <w:style w:type="paragraph" w:default="1" w:styleId="Normal">
    <w:name w:val="Normal"/>
    <w:qFormat/>
  </w:style>
  <w:style w:type="paragraph" w:styleId="Heading1">
    <w:name w:val="heading 1"/>
    <w:basedOn w:val="Normal"/>
    <w:next w:val="Normal"/>
    <w:qFormat/>
    <w:pPr><w:outlineLvl w:val="0"/></w:pPr>
    <w:rPr><w:b/><w:sz w:val="32"/></w:rPr>
  </w:style>
</w:styles>
Defaults, a default paragraph style and a heading style based on it.

What styles.xml holds

ElementMeaning
w:docDefaultsw:rPrDefault and w:pPrDefault: properties that apply before any style.
w:latentStylesWhat the built-in styles that are not yet in the document will look like in Word’s user interface: visibility and order, not formatting.
w:styleOne style.

w:style

ItemMeaning
w:type (attribute)paragraph, character, table or numbering.
w:styleId (attribute)The ID that text refers to. In Word, the name without spaces, for example Heading1.
w:default (attribute)This is the default style of its type: the one used when text names no style.
w:customStyle (attribute)The style is the user’s own, not built in.
w:nameThe style’s name, such as heading 1, which built-in styles are identified by.
w:basedOnThe style this one inherits from.
w:nextThe style of the next paragraph after pressing Enter.
w:linkThe linked style: a paragraph and character style pair.
w:uiPriority, w:semiHidden, w:unhideWhenUsed, w:qFormatHow Word lists the style.
w:pPr, w:rPrThe style’s paragraph and run properties.
w:tblPr, w:trPr, w:tcPr, w:tblStylePrTable style properties, and overrides for parts of a table such as the first row.

How formatting is resolved

A property’s final value comes from these, later ones overriding earlier ones:

  1. The document defaults (w:docDefaults).
  2. The table style, for text in a table.
  3. The numbering properties of a numbered paragraph.
  4. The paragraph style and its based-on chain.
  5. The character style and its based-on chain.
  6. Direct formatting on the paragraph or run.

Along a based-on chain, the nearest style that sets a property wins. The chain is followed until a style with no w:basedOn; a reader should guard against loops.

Some on/off properties are toggle properties: w:b, w:i, w:caps, w:smallCaps, w:strike, w:vanish and a few others. When a paragraph style and a character style both turn one on, the two cancel out: a run in a bold paragraph style with the Strong character style is not bold. Direct formatting does not toggle: it sets the value outright.