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Variables have to be used in the layer they are defined in. If you want to use a variable in multiple layers, you will have to add an identical variable to the other layer is it should be used in. This will make the variable only show up once in the variable editor.
You may choose to define a default value. A string field with a default would appear as such:
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If you have the same variable key in multiple layers, you do have the option to have the defaults be different (if you define one, you have to define all others). It will appear as such in the variable editor.
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Locals
Locals a are temporary values that are used internally to allow easily reusing certain values without repeating them over and over.
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