Many GnuTLS functions return opaque binary blobs represented by a gnutls_datum_t handle. A memory buffer holds the blobs' contents, which must be deallocated when the blob is no longer needed. These binary blobs become a x::gnutls::datum_t reference, a reference to a reference-counted object which may be freely passed around. When the last x::gnutls::datum_t reference to the underlying blob goes out of scope, the underlying object gets destroyed and the underlying memory buffer gets removed.

x::gnutls::datum_t is just a subclass of a x::vector. Its typical usage includes storing PEM-formatted objects and x::vector provides convenient methods to save and load the objects from files.