On 2013–10–10 Xan wrote:

> ! Undefined control sequence.
> 
> system          > tex > error on line 28 in file /home/xan/fems/proves-context/prova.tex: Undefined control sequence ...
> 
> 18       \starttikzpicture
> 19         [decoration={
> 20            markings,
> 21            mark=
> 22            between positions 0 and 1 step 0.5
> 23            with {
> 24             \draw (0,-2pt) -- (0,2pt);
> 25            }
> 26          }
> 27     ]
> 28 >>      \coordinate (F) at (0,0);

I can reproduce it now. Funnily it works on my regular installation
(same version). When I run it on a clean minimal installation I get
the same error. No clue what's going on and I don't have much time
to check at the moment.

Marco