Descriptor for variable-length text.
typedef struct _UMATextDescr { uint32 offset; /* Offset to beginning of data. */ uint32 count; /* Count of elements in the text. */ } UMATextDescr; typedef UMATextDescr * UMATextDescr ;
Support for random access to variable-length members of structures requires that the address of these members is derived from fixed size structures at known offsets within the main structure definition. There are 3 types of variable length member descriptor structures, all of which contain the offset required to locate the variable-length data. The 'offset' is considered relative to the base address of the parent structure of the variable-length member descriptor. Extra information concerning the variable length data may also be available.
Note that it is not possible to determine whether a variable-length data has been initialized before it is referenced. As a convention, setting the offset and count to 0 could be used to indicate an uninitialized variable-length data item.