Complex sentence: This allows representation of 4 planes which are mapped to the 4 planes currently used by unicode (planes 1-3 and 14) The two private use planes (15 and 16) and the currently unused planes (4-13) are not supported.
Split into simpler sentences: This allows representation of 4 planes which are mapped to the 4 planes currently used by unicode (planes 1-3 and 14). This means that the two private use planes (15 and 16) and the currently unused planes (4-13) are not supported.