There are numerous DAISY production tools available that support both the creation of the book structure and the recording of the human narration which is linked to the text content during the production process (or in some cases, in the post production process). Some also support 'importing' of an xhtml source file for Type 4 DAISY production with human narration, while still others support the production of a Type 4 DTB with synthetic speech (from a source file).