MIDL2172
The documentation lists this name without a value.
Documented in Win32
no [pointer_default] attribute specified, assuming [ptr] for all unattributed pointers in interface The DCE IDL implementation specifies that all pointers in each IDL file must be associated with pointer attributes. When an explicit pointer attribute is not assigned to the parameter or pointer type and no [ pointer_default ] attribute is specified in the IDL file, the full pointer attribute ptr is associated with the pointer. You can change the pointer attributes by using explicit pointer attributes, by specifying a [ pointer_default ] attribute, or by specifying the /ms_ext switch to change the default for unattributed pointers to [ unique ].