| base | For memory-based streams, this is the address of the first stream byte in memory. This field should always be set to NULL for disk-based streams. | 
| size | The stream size in bytes. | 
| pos | The current position within the stream. | 
| descriptor | This field is a union that can hold an integer or a pointer. It is used by stream implementations to store file descriptors or ‘FILE*’ pointers. | 
| pathname | This field is completely ignored by FreeType. However, it is often useful during debugging to use it to store the stream's filename (where available). | 
| read | The stream's input function. | 
| close | The stream;s close function. | 
| memory | The memory manager to use to preload frames. This is set internally by FreeType and shouldn't be touched by stream implementations. | 
| cursor | This field is set and used internally by FreeType when parsing frames. | 
| limit | This field is set and used internally by FreeType when parsing frames. |