B. When added to the header of a package or schema-level program, next to the AUTHID clause, it instructs Oracle to not make copies of partially compiled code in the SGA. Instead, all schemas that can execute that program will use the same copy of the partially compiled code.

C. When added after the parameter mode, IN OUT, this clause requests that Oracle pass your variable by reference, which means that Oracle will not make a copy of the variable for use within that subprogram.

D. NOCOPY is the default behavior for assignments of object type instances. This means that when I assign one instance to another, Oracle will not make a copy of my original instance, as happens with Java. Instead, all the attributes are copies to the new instance, and memory for the original instance is released.