Where does the C standard describe overflow of signed integers?

[Nicholas Nethercote]

Hi,

There was recently a very long thread about the overflow behaviour of 
signed integers in C.  Apparently this is undefined according to the C 
standard.  I searched the standard on this matter, and while I did find 
some paragraphs that described how unsigned integers must wrap around upon 
overflow, I couldn't find anything explicit about signed integers.  Can 
someone point me to the relevant part(s) of the standard?

Also, does anyone know what the required behaviour for Fortran integers is 
on overflow?

(I realise this isn't exactly on-topic for this list, but I thought it 
reasonable to ask since this topic was discussed so enthusiastically 
recently :)

Thanks very much.

Nick