16 assigned characters, 100% of them in a Symbol category.
Sixteen operators that describe how a character is built — left-and-right, above-and-below, surrounded on three sides — so that a Chinese character with no codepoint can be written as a formula from parts that do have one. The only block here that is a grammar for other characters rather than a set of them, and the closest thing in Unicode to blazon.
§The block entire
Every assigned character in the block, with its official name and codepoint.