Contains a map of what portions of the file are physically allocated versus what portions are sparse.
typedef struct zAllocationExtentElement_s { QUAD byteOffset; QUAD lengthBytes; } zAllocationExtentElement_s;
Specifies the starting byte offset in the file where this extent begins.
Specifies the length (in bytes) of the extent.
Each extent element identifies a starting offset and a length for an allocated portion of the file object. Every contiguously allocated portion of the file object is represented by exactly one extent list element. Unallocated or sparse portions of a file do not have an extent element returned for them.