Variables are “auto-typed” by default. This means that the type is automatically inferred from the value assigned to the variable in the Variables tab . If such a variable is wired to another variable or a block field, it inherits the source's type.

If you subsequently change the wiring so that the auto-typed variable is then wired to another variable or block field, its previously inferred type will be changed to the type of the new source.

Note that this means that type mapping (as described in Linking variables, block parameters, and block output fields) will not be necessary for variables that are auto-typed.