  Let $X$ be a simplicial complex with a piecewise linear function
$f:X\to\mathbb{R}$. The Reeb graph $Reeb(f,X)$ is the quotient of $X$, where we
collapse each connected component of $f^{-1}(t)$ to a single point. Let the
nodes of $Reeb(f,X)$ be all homologically critical points where any homology of
the corresponding component of the level set $f^{-1}(t)$ changes. Then we can
label every arc of $Reeb(f,X)$ with the Betti numbers
$(\beta_1,\beta_2,\dots,\beta_d)$ of the corresponding $d$-dimensional
component of a level set. The homology labels give more information about the
original complex $X$ than the classical Reeb graph. We describe a canonical
embedding of a Reeb graph into a multi-page book (a star cross a line) and give
a unique linear code of this book embedding.
