Use the following syntax to declare an IDL pointer:
*[*]...pointer_identifier
The * (asterisk) is the pointer operator, and multiple asterisks indicate multiple levels of indirection.
More:
Pointer Attributes in Parameters
Pointer Attributes in Function Results
Pointers in Structure Fields and Union Case
Resolving a Possible Pointer Ambiguity
Memory Management for Pointed-to Nodes
Advanced Memory Management Support
Use of Thread Handles in Memory Management
Rules for Using the Memory Management Routines