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R1276 / 1c:Mc-1

External Operation yields output of zero or one Scalar

Scalar constrains output of zero, one or many External Operation

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An External Operation may or may not return a value. If it does, we must specify the Scalar type of that value.

Since we are receiving a value from outside of our Domain, we know this value cannot be an instance reference.

For now at least, table values are not output by an External Operation.

A Scalar has many uses so a given Scalar may or may not defined the output of an External Operation.

And, of course, more than one External Operation might return the same type of value.