\defaultfontfeatures[ztm]
  {
  Extension = .otf ,
  UprightFont = ztm-Reg,
  BoldFont = ztm-Med,
  ItalicFont = ztm-RegIta,
  BoldItalicFont = ztm-MedIta,
  SlantedFont = ztm-RegObl,
  BoldSlantedFont = ztm-MedObl,  
  }