Figure 1

Simplified schema of the Meta-All database. Simplified UML [30] structure diagram of the database schema. The complete schema is available at the META-ALL project Web page. Rectangles symbolise classes (e.g. substance) without attributes and methods. Lines between classes symbolise relationships between the classes, called associations. Small diamonds at one of the ends of a line symbolise part-of relations. A black diamond means a composition (the single parts cannot exist on their own), an open diamond means an aggregation (the single part can exist on its own). A line with a triangle at one of the ends symbolises an inheritance relation (e.g. both metabolite class and enzyme class belong to the substance class). Numbers next to lines specify the allowed cardinalities for an instance of that class, for example, the 1..* at the line between metabolite and macromolecule means that a macromolecule consists of at least one (1) metabolite up to an unlimited (*) number of metabolites.