Changelog for version 0.2.0 lists, among other new operators, these three: "@ @@ $". However, I cannot find and mention or description of them in the pico-8.txt user manual, including manuals up to version 0.2.0c. Consider this a documentation "bug".

P.S. I cannot get single backticks to work here on BBS. Instead of formatting in-line code, they format the whole block (so act as if they were triple backticks).

In the meanwhile, someone on the Discord chat: "they’re shorthand for peek/peek2/peek4".

Also related: post ! undocumented.

These are in the manual now:

    peek2 addr
    poke2 addr val
    peek4 addr
    poke4 addr val

        16-bit and 32-bit versions. Read and write one number (val) in little-endian format:
            16 bit: 0xffff.0000
            32 bit: 0xffff.ffff

        addr does not need to be aligned to 2 or 4-byte boundaries.

    Alternatively, the following operators can be used to peek (but not poke), and are slightly faster:

        @ADDR  -- PEEK(ADDR)
        @@ADDR -- PEEK2(ADDR)
        $ADDR  -- PEEK4(ADDR)

(And ! was removed.)

Thanks for the heads-up!

Marked as resolved since v0.2.0d.