What does "Standard" mean in the datatype column of describe

Question

if you

Describe dbms_transform

PROCEDURE COMPUTE_TRANSFORMATION
 Argument Name                  Type                    In/Out
 ------------------------------ ----------------------- ------
 MESSAGE                        STANDARD                IN    
 TRANSFORMATION_SCHEMA          VARCHAR2                IN    
 TRANSFORMATION_NAME            VARCHAR2                IN    
 TRANSFORMED_MESSAGE            STANDARD                OUT

What does the STANDARD mean there?

Answer 1

Abstract Data Type?

http://www.psoug.org/reference/dbms_transform.html

Answer 2

The type is "<ADT_1>" which is defined in package standard.

According to the reference these

data types are generics, used specially within package STANDARD and some other Oracle packages. They are protected against other use; sorry. True generic types are not yet part of the language.