OP_EQUAL compares byte strings as-is. So it will push "false" because empty string is not the same as a single-byte string with 0x00 byte in it. Value "false" in turn is encoded as empty string, just like result of OP_0.

On 06 Nov 2015, at 10:37, Tier Nolan via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:

I meant not to use the OP_PUSH opcodes to do the push.

Does OP_0 give a zero length byte array?

Would this script return true?

OP_0
OP_PUSHDATA1 (length = 1, data = 0)
OP_EQUAL

The easiest definition is that OP_0 and OP_1 must be used to push the data and not any other push opcodes.

On Fri, Nov 6, 2015 at 9:32 AM, Oleg Andreev <oleganza@gmail.com> wrote:

> One and zero should be defined as arrays of length one. Otherwise, it is still possible to mutate the transaction by changing the length of the array.
>
> They should also be minimally encoded but that is covered by previous rules.

These two lines contradict each other. Minimally-encoded "zero" is an array of length zero, not one. I'd suggest defining this explicitly here as "IF/NOTIF argument must be either zero-length array or a single byte 0x01".

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