NULL pointer representation

[ruben-arm]

Currently, the guide seems to imply that NULL pointer is always represented with untagged all-zeroes value at:

Therefore, we have considered other options for
revocation, including tag-preserving \emph{permission}-zeroing (but tag
preservation) and wholesale replacement with \cconst{NULL} (i.e., the untagged
all~zero value).

If that's correct to assume in general that NULL pointer should be (or expected to be) represented with untagged all-zeroes value, would it be possible to explicitly state that in the guide?