The Solidity documentation has the following:
Internally, Solidity performs a revert operation (instruction
0xfd) for a require-style exception and executes an invalid operation (instruction
0xfe) to throw an assert-style exception.
When looking in the yellow paper, I cannot see the opcodes
0xfe documented. (The largest non-suicide opcode is
DELEGATECALL.) Where are
0xfe formally documented?