Every LE descriptor starts with a 4-byte field. The first byte specifies the descriptor type (scalar, array, structure or union). The remaining three bytes are zero unless they are set by the particular descriptor type.
The declare for a descriptor header is:
declare
1 dsc_Header based( sysnull() ),
2 dsc_Type fixed bin(8) unsigned,
2 dsc_Datatype fixed bin(8) unsigned,
2 * fixed bin(8) unsigned,
2 * fixed bin(8) unsigned;
The possible values for the dsc_Type field are:
declare dsc_Type_Unset fixed bin(8) value(0), dsc_Type_Element fixed bin(8) value(2), dsc_Type_Array fixed bin(8) value(3), dsc_Type_Structure fixed bin(8) value(4), dsc_Type_Union fixed bin(8) value(4);