The Itasca interface allows access to internal data structures and algorithms.

As such it is extremely dangerous – there is no way (even in theory) to prevent the user from writing code that will crash the program, or generate incorrect results.

Access to program data generally starts with the IProgram interface, which can be thought of as the root of a tree of all the interfaces available.

In general program specific data (Flac3D, 3DEC, PFC, etc) will be available in the interface IFLAC3D, which is defined differently for each program.