Short jumps are +127/-128 bytes, near for anything else, as a "short" answer. :)
Nasm defaults to "near" for unconditional jumps, to "short" for conditional jumps. Nasm will advise you if "short" won't work.
Since, as you've observed, the instruction set reference has been removed from the Nasm Manual... I guess you'll have to consult manufacturers docs for instruction information.
Or you could look at the *old* manual. :)
Far jumps reload the cs register, and are probably not what you want unless you're writing an OS or a large dos program - the latter would be silly, these days.
For a really easy solution, give Nasm the "-O" switch, and let it determine whether "near" is needed, or if "short" will reach.
Best,
Frank
