It would be useful if there was an easy and clean way to draw interrupted lines, the kind of thing used to evoke a discontinuity:
-------//------
Right now, I used the following hack, which gives a satisfying result:
\path (X1.center) -- ++(60:2.5)
node[midway,sloped,inner sep=0] (skip){$//$}
node (R1) {$R_1$};
\draw (X1) -- (skip) -- (R1);
But It would be better if something cleaner was available, with options for different styles of interruption symbols.
(And while I'm here: thank you very much for TikZ.)
See https://github.com/pgf-tikz/pgf/issues/589