diff -r b4f517f893f1 -r cfe34e335f2c QDouble.st
--- a/QDouble.st	Sat Aug 31 16:12:21 2019 +0200
+++ b/QDouble.st	Sat Aug 31 16:12:38 2019 +0200
@@ -1,5 +1,3 @@
-"{ Encoding: utf8 }"
-
 "
  COPYRIGHT (c) 2017 by eXept Software AG
 	      All Rights Reserved
@@ -2264,7 +2262,7 @@
      1 asQDouble exp_withAccuracy:LongFloat epsilon     2.71828182845904523536
      1 asQDouble exp_withAccuracy:Float epsilon         2.71828182845904522671
 
-							1.7392749415205010473946813036112352261479840577250084... × 10^18
+							1.7392749415205010473946813036112352261479840577250084... × 10^18
 
      42 asQDouble exp_withAccuracy:QDouble epsilon      NAN
      42 asQDouble exp_withAccuracy:LongFloat epsilon    1.73927494152050104739e18
@@ -3044,19 +3042,25 @@
 !QDouble methodsFor:'testing'!
 
 isFinite
+    "return true, if the receiver is a finite float (not NaN and not +/-INF)"
+
     ^ self d0 isFinite
 
     "Created: / 17-06-2017 / 03:40:30 / cg"
 !
 
 isInfinite
+    "return true, if the receiver is an infinite float (+Inf or -Inf)."
+
     ^ self d0 isInfinite
 
     "Created: / 15-06-2017 / 01:57:57 / cg"
 !
 
 isNaN
-    ^ self d0 isNaN
+     "return true, if the receiver is an invalid float (NaN - not a number)"
+
+   ^ self d0 isNaN
 
     "Created: / 15-06-2017 / 01:57:35 / cg"
 !