  We prove that, for an interval $X\subseteq \mathbb R$ and a normed space $Z$
diagonals of separately absolute continuous mappings $f:X^2\to Z$ are exactly
such mappings \mbox{$g:X\to Z$} that there is a sequence $(g_n)_{n=1}^{\infty}$
of continuous mappings $g_n:X\to Z$ with $\lim\limits_{n\to\infty}g_n(x)=g(x)$
and \mbox{$\sum\limits_{n=1}^{\infty}\|g_{n+1}(x)-g_n(x)\|<\infty$} for every
$x\in X$.
