-// a stack or volume) we need to check the corresponding images are
-// coherent:
-// - they all share the same X dimensions
-// - they all share the same Y dimensions
-// - each file a Z dimension of 1
-// - they all share the same type ( 8 bit signed, or unsigned...)
-bool vtkGdcmReader::CheckFileCoherence()
+// a stack or volume) we need to check that the corresponding images/volumes
+// to be loaded are coherent i.e. to make sure:
+// - they all share the same X dimensions
+// - they all share the same Y dimensions
+// - they all share the same ImageType ( 8 bit signed, or unsigned...)
+//
+// Eventually, we emit a warning when all the files do NOT share the
+// Z dimension, since we can still build a stack but the
+// files are not coherent in Z, which is probably a source a trouble...
+// When files are not readable (either the file cannot be opened or
+// because gdcm cannot parse it), they are flagged as "GDCM_UNREADABLE".
+// This method returns the total number of planar images to be loaded
+// (i.e. an image represents one plane, but a volume represents many planes)
+int vtkGdcmReader::CheckFileCoherence()