This attribute is a complex attribute which can describe MaxOccur or MinOccur.

The category attribute describes the Port type. The value of this attribute is user-defined. Only ports with the same category value are allowed to be connected. Example: category = “MaterialFlow”

This CAEX Interface allows connecting this Port with a number of other ports on an abstract level. The internal relations between single Port interfaces are not described in this way.

This attribute shall be used to describe the direction of the Port. Values shall be one of the following: “In” or “Out” or “InOut”. Ports with the direction “In” can only be connected to ports with the direction “Out” or “InOut” and ports with the direction “Out” can only be connected with ports with the direction “In” or “InOut”. Ports with the direction “InOut” can be connected to Ports of arbitrary direction. Examples: Direction =”Out” (e.g. a plug) Direction = “In” (e.g. a socket) Direction = “InOut” This information can be used e.g. in order to prove the validity of a connection.