Aspects

Aspects of an exchange format:

• ``lexical'' layer -- how to parse the data stream into object
• ``logical'' layer -- what is the structure of the object
• ``semantics'' layer -- what is the meaning of the object

The lexical and logical layers are the more important aspects of an exchange format. The better they are designed, the easier it is to exchange information. The semantics layer is often not needed to accomplish the exchange of information between two systems.

The lexical layer should be designed to support multiple logical layers. That is, objects of different structures can be laid out in a data stream using the same lexical layer.