The minimum DITA adoption requires that you migrate the current sources of content in XML. You do, however, have the flexibility to decide which sources to migrate when, and how much structure to apply to the migrated content. Many teams have a large amount of legacy information that was authored in a variety of sources. Some teams may choose to migrate only the content that will require updates in the future. Other teams migrate everything, but do not move the content into typed topics; instead they move the content en masse into generic topics, which are the least restrictive topic type and hence require the least amount of content restructuring. However, the generic topic type also provides the least amount of semantic value.
Another way that teams save time at this level is to defer splitting the content into discrete topics and simply recreate their existing document-focused structure by nesting multiple topics within a single file. For example, recreating chapters
as DITA files allows you to continue to store all the chapter content in a single file. While this strategy takes less time than restructuring the content into units based on subject, it does not provide small enough units of information to enable
easy reorganization of the content into multiple deliverables.
Because XML separates the formatting from the content, the transform for each deliverable type applies the styles and formatting defined in the cascading style sheets (CSS) when you generate or publish the deliverable. Although the DITA
Open Toolkit provides default processing for multiple deliverable types, you must customize the transforms to generate deliverables that meet the style, standard, and branding requirements for your organization.
For more information, see http://dita.xml.org/wiki/level-one-topics.