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prop: input-port
prop: output-port
Version: 4.2.1
12.1.8 Structures as Ports

The prop:input-port and prop:output-port structure type properties identify structure types whose instances can serve as input and output ports, respectively.

Each property value can be either of the following:

Some procedures, such as file-position, work on both input and output ports. When given an instance of a structure type with both the prop:input-port and prop:output-port properties, the instance is used as an input port.