static packable_tree *recursive_unpack(basis::byte_array &packed_form,
packable_tree_factory &creator);
//!< unpacks a tree stored in "packed_form" and returns it.
- /*!< if NIL is returned, then the unpack failed. the "creator" is needed
+ /*!< if NULL_POINTER is returned, then the unpack failed. the "creator" is needed
for making new derived packable_tree objects of the type stored. */
// standard pack, unpack and packed_size methods must be implemented by the derived tree.