In this section, the DDL categories that describe the properties
of data items are presented. Figures 
and
illustrate the schema for these categories.
Figure:
The schema of DDL definitions that describe data items (Part I)
In this figure, boxes surround data items which belong to the
same category. Category identifiers are given in large font
and item names are given in small font. Parent-child relationships
are specified by lines connecting data items with the arrow pointing
at the parent item. Key items within a category are identified
by a preceding black dot.
Figure:
The schema of DDL definitions that describe data items (Part II)
In this figure, boxes surround data items which belong to the
same category. Category identifiers are given in large font
and item names are given in small font. Parent-child relationships
are specified by lines connecting data items with the arrow pointing
at the parent item. Key items within a category are identified
by a preceding black dot.