meshS for a Möbius strip

Dear all,

Is it possible to build a meshS for a Mobius strip? I am trying the following code mobius.edp (508 Bytes), with either movemesh23 or square3 functions. Both methods fail with similar error:

Bad orientation: The adj border element defined by [ 100 201 ] is oriented in the same direction in element …

Is it possible to find a workaround, or is it just impossible because the Möbius strip is a non-orientable surface?
Thank you for your help.

yes, we suppose the surface must be orientable,