The portrayal catalogue consists of the feature portrayal, portrayal rule and external function, as
shown in Figure 27. To produce different products, several portrayal catalogues may exist, portraying
one or more datasets. The portrayal catalogue relates to one or more portrayal specifications, and
one portrayal specification may be used in one or more portrayal catalogues. A portrayal rule consists
of two parts: a query statement that can use one or more external functions, and one or more action
statements.