Hi there,
Sorry for the later reply,If you want to do solt in your board, the minimum solt width must over 0.8mm, please put the file in board outline layer（NPTH） or mechanical layer（milling）. As some customers use Altium to desin ,when you generate the gerber file have 2 drill files, please send the through hole TXT and slot hole TXT togerher to us.
This is the rule of planelizing:http://www.seeedstudio.com/blog/2011/11/03/letters-from-customerspcb-penalization/.
Regards,
Dingding