This type is a list of HL_CompoundTypeAttributes. The reason why it's called ``Description'' is that it acts more like meta data than actual data, since it's just a collection of other nodes which may contain data, and is therefore more of a description than anything else. It is structured like this:
typedef struct { char typename[256]; /* the list's name */ unsigned long objno[2]; /* markers used to tag nodes in the list */ size_t size; /* size of this data type */ int nAttrs; /* the number of attributes in the list */ int nAllocAttrs; /* the number of allocated attributes */ HL_CompoundTypeAttribute** attrs; /* the attributes themselves */ } HL_CompoundTypeDescription;