c1, c2 and behave like a Merkle proof for both. See merkel update cells page
for details. The level of a merkle update cell, 0 <= l < 3, is determined as max{Lvl(c1) - 1, Lvl(c2) - 1, 0}.
Each Merkle update cell serializes as follows:
- one tag byte with value
0x04; - the 256-bits first higher hash of the referenced cell
c1or the representation hash ofcif its level equals zero; - the same for the second reference
c2; - 2 bytes that store the depth of the old deleted subtree that was replaced by the reference
c1; - 2 bytes that store the depth of the new deleted subtree that was replaced by the reference
c2.