A port the node type does not declare is outside exposure checking
The rule
Normative: this is the rule
A port that appears on an edge but is not declared in the node type's metadata (a dynamic or author-defined port) is out of scope for R7, and an edge over it is not refused for being unexposed.
Rule identifiers are permanent and are never renumbered. Each implementation publishes its own standing against these rules; this specification does not.spec 1.0-draft · R7.d · changed in spec 1.0