Re: incremental regexp search string

[Richard M. Stallman]

    Currently, when I write to another person telling him of an
    incremental regexp search expression with some special constructs used
    as ordinary characters, it appears I must say the expression in words:

        two left square brackets followed by a space and a number between 0
        and 9.

    and he must type   [[ [0-9]+

I do not follow you.  
That would not be the correct input for regexp isearch.
It is necessary to type \[\[ [0-9]+
to find such places.