To reference an external object, the IMPORTS statement must be used to identify both the descriptor and the module in which the descriptor is defined, where the module is identified by its ASN.1 module name.
Note that when symbols from "enterprise-specific" information modules are referenced (e.g., a descriptor), there is the possibility of collision. As such, if different objects with the same descriptor are IMPORTed, then this ambiguity is resolved by prefixing the descriptor with the name of the information module and a dot ("."), i.e.,
(All descriptors must be unique within any information module.)
Of course, this notation can be used even when there is no collision when IMPORTing symbols.
Finally, the IMPORTS statement may not be used to import an ASN.1 named type which corresponds to either the SEQUENCE or SEQUENCE OF type.