Index: sources/gui/qml/globals/Variables.qml
===================================================================
diff -u -r5c21e83a3fdc897cb99ac62e1cec0213f411cd73 -r6f73e3ec5ba15c5c6ecc59191462e64e3bc36dfc
--- sources/gui/qml/globals/Variables.qml	(.../Variables.qml)	(revision 5c21e83a3fdc897cb99ac62e1cec0213f411cd73)
+++ sources/gui/qml/globals/Variables.qml	(.../Variables.qml)	(revision 6f73e3ec5ba15c5c6ecc59191462e64e3bc36dfc)
@@ -201,6 +201,11 @@
                 return notSetVariableText
     }
 
+    // it is prefered to use the regExp instead of the RegExpValidator
+    // otherwise an extra RegExpValidator object will always created here.
+    readonly property var regExp_PatientID: /[A-Za-z0-9]{1,20}/
+
+
     readonly property string preTreatmentStepLabelCreate            : qsTr("CREATE"   )
     readonly property string preTreatmentStepLabelConfirm           : qsTr("CONFIRM"  )
     readonly property string preTreatmentStepLabelPriming           : qsTr("PRIME"    )