Specialisation elements
Elements used primarily for specialisation are categorised as specialisation elements.
The DITA specialisation elements are those that are used for architectural purposes rather than for semantic mark-up. In many cases, they are elements provided so that new elements can be specialised from them.
Specialisation
		elements include: 
	 
 
  - boolean
 - data
 - data-about
 - foreign
 - index-base
 - unknown