diff --git a/bundles/org.openhab.core.model.persistence/src/org/openhab/core/model/persistence/Persistence.xtext b/bundles/org.openhab.core.model.persistence/src/org/openhab/core/model/persistence/Persistence.xtext
index f46d46c649..49bf87c30b 100644
--- a/bundles/org.openhab.core.model.persistence/src/org/openhab/core/model/persistence/Persistence.xtext
+++ b/bundles/org.openhab.core.model.persistence/src/org/openhab/core/model/persistence/Persistence.xtext
@@ -32,7 +32,7 @@ FilterDetails:
 ;
 
 ThresholdFilter:
-	'>' (relative?='%')? value=DECIMAL unit=STRING?
+	'>' (relative?='%')? value=DECIMAL unit=(UNIT|STRING)?
 ;
 
 TimeFilter:
@@ -40,27 +40,27 @@ TimeFilter:
 ;
 
 EqualsFilter:
-   '=' values+=STRING (',' values+=STRING)*
+	'=' values+=STRING (',' values+=STRING)*
 ;
 
 NotEqualsFilter:
-   '!' values+=STRING (',' values+=STRING)*
+	'!' values+=STRING (',' values+=STRING)*
 ;
 
 IncludeFilter:
-  '[]' lower=DECIMAL upper=DECIMAL unit=STRING?
+	'[]' lower=DECIMAL upper=DECIMAL unit=(UNIT|STRING)?
 ;
 
 NotIncludeFilter:
-  '][' lower=DECIMAL upper=DECIMAL unit=STRING?
+	'][' lower=DECIMAL upper=DECIMAL unit=(UNIT|STRING)?
 ;
 
 
 PersistenceConfiguration:
 	items+=(AllConfig | ItemConfig | GroupConfig | ItemExcludeConfig | GroupExcludeConfig)
-	   (',' items+=(AllConfig | ItemConfig | GroupConfig | ItemExcludeConfig | GroupExcludeConfig))* 
+		(',' items+=(AllConfig | ItemConfig | GroupConfig | ItemExcludeConfig | GroupExcludeConfig))* 
 	((':' ('strategy' '=' strategies+=[Strategy|ID] (',' strategies+=[Strategy|ID])*)? 
-		 ('filter' '=' filters+=[Filter|ID] (',' filters+=[Filter|ID])*)?) 
+			('filter' '=' filters+=[Filter|ID] (',' filters+=[Filter|ID])*)?) 
 		| ';')
 ;
 
@@ -78,17 +78,21 @@ GroupConfig:
 ;
 
 ItemExcludeConfig:
-    '!' itemExclude=ID
+	'!' itemExclude=ID
 ;
 
 GroupExcludeConfig:
-    '!' groupExclude=ID '*'
+	'!' groupExclude=ID '*'
 ;
 
 AliasConfiguration:
-    item=ID '->' alias=(ID|STRING)
+	item=ID '->' alias=(ID|STRING)
 ;
 
 DECIMAL returns ecore::EBigDecimal :
 	'-'? INT ('.' INT)?
 ;
+
+UNIT:
+	(('^' INT)|'²'|'³'|'/'|'*'|'·'|'°'|'µ'|'%'|'‰'|'Ω'|'Å'|'('|')'|ID)+
+;