|DITA authoring concepts / Distinction between format and style, and data and metadata|
The philosophical differences between style-based authoring and semantic authoring present the greatest challenges for new DITA authors.
In style-based authoring, the structure of a document is defined by the styles applied to its components. For example, a second level heading might be defined in a document by the application of a heading 2 style. Likewise, the presentational style of the deliverable document is defined by styles embedded within the authored document. For example, text to be indented by 2 cm might be defined in the paragraph by the application of an Indent2 style.
The separation of content and form in DITA sees the upper-level structure being defined outside the content (in the ditamap), and the presentational style being applied in a publishing process entirely separate from the authoring process. The presentational form for a document can be unknown to the DITA author. The same topic can have different appearances and different structures when the same source content is used to produce different deliverable documents.
For example, a DITA topic in one deliverable document may have a heading 2 style applied during processing, but the same topic in a different deliverable document may have heading 4 applied. The publishing rules determine the mapping of DITA semantic elements to output presentational form.
These differences between style-based authoring and semantic authoring present the greatest challenge to new DITA authors.