Indents cannot be directly inherited, in the sense that an indent set in a parent tag has no effect on the current mapping. Indents can however be indirectly affected by Left or Right margins set in parent tags, as these can affect the current Left or Right margin on which the indent is based.

Also note that indents apply to the current paragraph only, where a paragraph is defined as a (non-empty) text fragment bounded by two block (start or end) tags. Consider the XML fragment:

<chapter id="1">
  <section id="1.1">
    <title>Title with an Indent</title>
    <para> . . .

Which mapping controls the indent of the title text? The general rule is that the indent is controlled by the nearest preceding Block (start) tag. So if chapter and section are Block tags and title is an In-line, then it is the section mapping that specifies the title indent. However in the case of a caption with optional label:

<caption><label>Table 28</label>
  Allowable Tax Deductions

the caption will not be indented at all if caption and label are both Blocks This is because the paragraph Allowable Tax Deductions is not at the start of the caption content. However the label text Table 28 could be indented directly by label. Likewise any text subsequently inserted between the two start tags could be indented by caption.

In general fine paragraph control such as indenting can only be applied when the text to be indented is introduced by a start tag of type Block. If you need to apply indents to text like the above caption, you must ensure that appropriate markup exists in the source document or is added in a separate preprocessing phase.