diff --git a/code/source_damage_isoBrittle.f90 b/code/source_damage_isoBrittle.f90
index d133f100f..0e87c7650 100644
--- a/code/source_damage_isoBrittle.f90
+++ b/code/source_damage_isoBrittle.f90
@@ -272,9 +272,10 @@ subroutine source_damage_isoBrittle_deltaState(C, Fe, ipc, ip, el)
    stiffness(6,6), &
    strainenergy
 
- phase = mappingConstitutive(2,ipc,ip,el)
- constituent = mappingConstitutive(1,ipc,ip,el)
- instance = source_damage_isoBrittle_instance(phase)
+ phase = mappingConstitutive(2,ipc,ip,el)                                                            !< phase ID at ipc,ip,el
+ constituent = mappingConstitutive(1,ipc,ip,el)                                                      !< state array offset for phase ID at ipc,ip,el
+ ! ToDo: capability for multiple instances of SAME source within given phase. Needs Ninstance loop from here on!
+ instance = source_damage_isoBrittle_instance(phase)                                                 !< instance of damage_isoBrittle source
  sourceOffset = source_damage_isoBrittle_offset(phase)
 
  stiffness = C