  We prove that if $\leq$ is an analytic partial order then either $\leq$ can
be extended to a (boldface) $\Delta^1_2$ linear order similar to an antichain
in $2^{<\omega_1}$ ordered lexicographically or a certain Borel partial order
$\leq_0$ embeds in $\leq.$ Some corollaries for analytic equivalence relations
are given, for instance, if $E$ is a $\Sigma^1_1[z]$ equivalence relation such
that $E_0$ does not embed in $E$ then $E$ is determined by intersections with
E-invariand Borel sets coded in $L[z]$.
