1. A method of creating an updatable search tree identifying a specific item within an item class, said method comprising: (a) accessing a collection of unique registrable item samples belonging to said item class, each registrable item sample being a representation of a different target item and having a unique identification (ID) code identifying its corresponding target item; (b) identifying a, separate and corresponding, registrable set of item descriptors for each of said registrable item samples; (c) creating a composite collection of item descriptors from the separate registrable sets of item descriptors into; (d) organizing said composite collection of item descriptors into a hierarchical tree structure according to relations in the item descriptors, each leaf node of said hierarchical tree being indexed according to its leaf index list, said leaf index list being comprised of the ID's of the target items corresponding to the item descriptors within the leaf node; (e) accessing a new registrable item having a unique identification (ID) code identifying its corresponding target item; (f) identifying a new registrable set of item descriptors for said new registrable item; (g) distributing the new registrable set of item descriptors into said hierarchical tree according to said relations in the item descriptors by which said hierarchical tree is organized, each leaf node of said hierarchical tree that receives any part of said new registrable set of item descriptors being a target leaf node, and each target leaf node being subjected to an incremental tree modification of said hierarchical tree using only the item descriptors within the target leaf node, said incremental tree modification creating at least two additional child nodes under said target leaf node, each of said additional child nodes being indexed to the ID's on its index list, said index list including at least the IDs of the target items corresponding to the item descriptors within it, the resultant modified hierarchical tree being said updatable search tree.