CF23 — ENDXC (b x – c), if x 6= 0, creates a special or exotic cell
(cf. 3.1.2) from Builder b. The type of the exotic cell must be stored
in the first 8 bits of b. If x = 0, it is equivalent to ENDC. Otherwise
some validity checks on the data and references of b are performed
before creating the exotic cell
D739 — XCTOS (c – s ?), transforms an ordinary or exotic cell into a
Slice, as if it were an ordinary cell. A flag is returned indicating whether
c is exotic. If that be the case, its type can later be deserialized from
the first eight bits of s
https://github.com/ton-blockchain/docs/blob/master/docs/smart-contracts/tvm-instructions/instructions.md is missing some primitives: