Asbru's Reference Manual - Asbru Version 7.2

elements contain a set of alternative children, i.e. exactly one of them must be used in place of the alternative element. They are translated to alternatives (or-groups) in the DTD. Therefore, the name of an abstract element is not shown in the DTD and therefore not by the XML–editor. Still in this document, they are retained since they greatly contribute to clarity. Also, they are often used to use the same group of alternatives in different elements. Aliases are used in cases where elements with different names share the same syntactic structure. They appear as distinct elements in the DTD but are specified together in the HSL–file to ease maintenance. Note that the aliasing refers to the syntax only. The semantics of such twins are often contradictory (e.g., is-at-end and is-at-start). The following table gives an example of how elements are described in this document. 1E.g. in numerical-constant, the value is shown after the unit instead before it, which would be more intuitive.