可以使用：References (Alias types)

References (Alias types)

You can use the user-defined derived data type to create an alternative name for a variable, constant or function block. Create your references as objects in the Object Organizer under the register card Data types. They begin with the keyword TYPE and end with END_TYPE.

Syntax:

TYPE <Identifier>: <Assignment term>;
END_TYPE

Example:

TYPE message:STRING[50];
END_TYPE;

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