Quoth David Bremner on Feb 03 at  8:50 pm:
> On Mon, 30 Jan 2012 18:01:15 +0200, Jani Nikula <jani@nikula.org> wrote:
> > On Jan 30, 2012 4:38 PM, "Tomi Ollila" <tomi.ollila@iki.fi> wrote:
> > >
> > > > +
> > > > +* Indent is 4 spaces with mixed tabs/spaces and a tab width of 8.
> > > > +  Tabs should be only at the beginning of the line.
> > >
> > > So, after initial indentation (with tabs) there should not be further
> > > tabs? We'll be using the former instead of the latter in these 2 below?
> 
> Ah, I only meant to explain what whitespace-mode complains about, namely
> 
> <space><space><space><space><tab>x=1;
> 
> as opposed to 
> 
> <tab<space><space><space><space><tab>x=1;
> 
> I'm not sure it's that important, but apparently if it stays in the
> style guide it needs rewording.

Any indentation style this difficult to explain can't be a good idea.
How about,

* Indent is 4 spaces with mixed tab/spaces and a tab width of 8.
  (Specifically, a line should begin with zero or more tabs followed
  by fewer than eight spaces.)