Questions about freebsd-update

[Quartz]

>>> The tools involved here are already part of the base system (except
>>> they got manually removed, which renders the OS somehow incomplete).
>>> A system installation typically uses compiler, assembler, linker,
>>> installer, and make, which are all contained in the base distribution
>>> of the OS.
>>
>> Wait.... isn't all the build stuff part of the 'src' option during
>> install?
>
> No. The "src" distribution contains the sources which will
> be available in the /usr/src subtree.
>
>> If you unselect that, how does make/install apply patches if
>> the files it's patching aren't there?
>
> It doesn't do that, but the tools make, install, and patch
> themselves will be available.

I understand that the utils themselves are still installed regardless, 
but in order for the 'patch' command to have something to patch against, 
doesn't 'src' have to be installed also? Otherwise, are you saying that 
the sources to all the system bits are always installed? And if *that's* 
true... then what the heck is 'src' installing then?