That's because I did not directly define the libraw_data_t structure (a record in pascal) in the wrapper. I am simply using a general void* (a Pointer type in pascal) instead. Means any pascal program using this wrapper has access only to the pointer itself (to the libraw_data_t structure) but not the structure fields directly.

Reason is simple: All subsequent calls after libraw_init simply accepts the pointer (to structure) and they just do their job.

There was no reason yet to directly define the libraw_data_t record in the wrapper because no direct access to any field was required.