The decomposition of Hangul Jamo clusters encoded in Unicode is derived from Unicode 2.0.14 data file ( slightly modified by me ) and the list of additional Jamo clusters not encoded in Unicode was compiled by Microsoft Korea. This list is to supplement the list made available by Microsoft (Appendix B) as a part of the opentype developer documents.
Entries marked as decomposition mapping are for decomposition. All others are only for composition. Entries under the heading of not encoded in U+1100 block are listed only for opentype font development and rendering/layout engine development. As such they should not be used for composition/decomposition of Hangul Jamos in text processing. In fact, for text processing purpose, entries marked tagged with ( decomposition mapping ) are only required because the rest can be derived by applying the algorithm described in UAX #15 or equivalents.