procedure
<ident>.extend { <data-block> }
A procedure to extend a structure class definition, by adding additional static elements.
<ident> may be a structure, gstructure, compound, dbstructure or treenode class. It cannot be an instance of one of these but must be the class name.
All new elements are assumed to be static elements, even if the initial "static" qualifier is omitted. Refer to the structure command for details of <data-block> contents.
This is a system procedure and cannot be changed.