minId = self.firstSeqId
maxId = minId + self.symmetry.segmentLength
chain = self.getByNavigation('symmetry', 'molSystemSymmetrySet', 'molSystem', ('chains', self.chainCode))
if chain is None:
raise ApiError("No chain found for %s" % self)
result = [x for x in chain.sortedResidues() if minId <= x.seqId < maxId]