  Consider a complete flag $\{0\} = C_0 < C_1 < \cdots < C_n = \mathbb{F}^n$ of
one-point AG codes of length $n$ over the finite field $\mathbb{F}$. The codes
are defined by evaluating functions with poles at a given point $Q$ in points
$P_1,\dots,P_n$ distinct from $Q$. A flag has the isometry-dual property if the
given flag and the corresponding dual flag are the same up to isometry. For
several curves, including the projective line, Hermitian curves, Suzuki curves,
Ree curves, and the Klein curve over the field of eight elements, the maximal
flag, obtained by evaluation in all rational points different from the point
$Q$, is self-dual. More generally, we ask whether a flag obtained by evaluation
in a proper subset of rational points is isometry-dual. In [3] it is shown, for
a curve of genus $g$, that a flag of one-point AG codes defined with a subset
of $n > 2g+2$ rational points is isometry-dual if and only if the last code
$C_n$ in the flag is defined with functions of pole order at most $n+2g-1$.
Using a different approach, we extend this characterization to all subsets of
size $n \geq 2g+2$. Moreover we show that this is best possible by giving
examples of isometry-dual flags with $n=2g+1$ such that $C_n$ is generated by
functions of pole order at most $n+2g-2$. We also prove a necessary condition,
formulated in terms of maximum sparse ideals of the Weierstrass semigroup of
$Q$, under which a flag of punctured one-point AG codes inherits the
isometry-dual property from the original unpunctured flag.
