+[slc:executionSpec] > nt:unstructured, mix:referenceable, mix:title
+- slc:name (STRING)
++ * (slc:executionSpecAttribute) *
+
+[slc:executionSpecAttribute] > nt:base
+mixin abstract
+- slc:isImmutable (BOOLEAN) m
+- slc:isConstant (BOOLEAN) m
+- slc:isHidden (BOOLEAN) m
+
+[slc:primitiveSpecAttribute] > slc:executionSpecAttribute