When setting exdata, the pointer specified with a particular index is saved,
and returned on a subsequent "get" call. If the application is going to
release the data, it must make sure to set a B<NULL> value at the index,
When setting exdata, the pointer specified with a particular index is saved,
and returned on a subsequent "get" call. If the application is going to
release the data, it must make sure to set a B<NULL> value at the index,