These conventions are the primary focus of this article. The second defines the organization of model diagrams. Positional conventions dictate how entities are laid out. These will be discussed at the end of the article. And finally, there are conventions about how the meaning of a model may be conveyed.
Semantic conventions describe standard ways for representing common business situations.
These three sets of conventions are, in principle, completely independent of each other. Given any of the syntactic conventions described here, you can follow any of the available positional or semantic conventions. In practice, however, promoters of each syntactic convention typically also promote at least particular positional conventions. In evaluating syntactic conventions, it is important to remember that data modeling has two audiences. The first is the user community, that uses the models and their descriptions to verify that the analysts in fact understand their environment and their requirements.