[Therion] conversion vtopo/therion : .tro ->.th

Dear all This is my first message on the list. To introduce me, I mainly practice caving in the French Alps, around Grenoble. I discovered therion 1.5 years ago and really enjoy this soft. I apologize because I think this question is often submitted, but I did not find the answer on the archive of the list, neither on the wiki : I would like to make a synthesis on a medium cave (about 5km and 800 stations), and most of the former surveys have been done with Vtopo (a single 830 lines file .tro). Since Vtopo and therion syntaxes are quite similar for topographic survey, does anybody get a script to convert vtopo files (.tro) to therion file (.th) ? (I work under linux). Martin