diff -r 546f2090ce12 -r a47c4227a0c6 slides.sty
--- a/slides.sty	Fri Sep 23 15:22:33 2016 +0100
+++ b/slides.sty	Sat Sep 24 08:31:04 2016 +0100
@@ -16,6 +16,8 @@
 
 \newcommand{\tttext}[1]{{\consolas{#1}}}
 
+\newcommand{\ZERO}{\mbox{\bf 0}}
+\newcommand{\ONE}{\mbox{\bf 1}}
 \newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}%
 \newcommand{\slidecaption}{}