LinestringZM is a really old data structure … as far as I remember
I do not know why the importer converts elements to ZM. Originally the elements where linestring25D as you mentioned. Anyway, in the mean time it would be good thing to publish the ocx that handles this check.
On the other hand (subject form other conversation) I hope the issue of the ecw images get solved as well.
Thank you for you patience !!
Alex