This type is designed to describe an individual node with a complicated structure, ie. one which consists of more than atomic data types. It contains all the information required to interpret the contents of the node:
typedef struct { char attrname[256]; /* the Attribute's name */ size_t offset; /* the offset to where the data begins */ char format[256]; /* the string representation of the atomic data type */ int ndims; /* the number of dimensions in the array */ size_t dims[4]; /* the dimensions of each of ndims */ } HL_CompoundTypeAttribute;