code: def _assignRootname(self, chip):
          
          extname=self._image[self.scienceExt,chip].header["EXTNAME"].lower()
          extver=self._image[self.scienceExt,chip].header["EXTVER"]
          expname = self._rootname
  
          # record extension-based name to reflect what extension a mask file corresponds to
          self._image[self.scienceExt,chip].rootname=expname + "_" + extname + str(extver)
          self._image[self.scienceExt,chip].sciname=self._filename + "[" + extname +","+str(extver)+"]"
          self._image[self.scienceExt,chip].dqrootname=self._rootname + "_" + extname + str(extver)
          # Needed to keep EXPNAMEs associated properly (1 EXPNAME for all chips)
          self._image[self.scienceExt,chip]._expname=expname
          self._image[self.scienceExt,chip]._chip =chip
docs: Assign a unique rootname for the image based in the expname.