  Let $(T,X)$ with phase mapping $(t,x)\mapsto tx$ be a semiflow on a compact
$\textrm{T}_2$-space $X$ with phase semigroup $T$ such that $tX=X$ for each $t$
of $T$. An $x\in X$ is called an \textit{a.a. point} if $t_nx\to y,
x_n^\prime\to x^\prime$ and $t_nx_n^\prime=y$ implies $x=x^\prime$ for every
net $\{t_n\}$ in $T$. In this paper, we study the a.a. dynamics of $(T,X)$; and
moreover, we present a complete proof of Veech's structure theorem for a.a.
flows.
