diff --git a/ontology/saref4ehaw.ttl b/ontology/saref4ehaw.ttl
index c1533f9b792f48a10cd648129ff166061737c01b..9da0cd77ff50689600148906c597c357fd69d3cd 100644
--- a/ontology/saref4ehaw.ttl
+++ b/ontology/saref4ehaw.ttl
@@ -9,6 +9,7 @@
 @prefix s4ehaw: <https://saref.etsi.org/saref4ehaw/> .
 @prefix s4envi: <https://saref.etsi.org/saref4envi/> .
 @prefix s4wear: <https://saref.etsi.org/saref4wear/> .
+@prefix ssn-system: <http://www.w3.org/ns/ssn/systems/> .
 @prefix dcterms: <http://purl.org/dc/terms/> .
 @base <https://saref.etsi.org/saref4ehaw/> .
 
@@ -333,6 +334,14 @@ s4ehaw:isDescribedBy rdf:type owl:ObjectProperty ;
                      rdfs:label "is described by"@en .
 
 
+###  https://saref.etsi.org/saref4ehaw/precision
+s4ehaw:precision rdf:type owl:ObjectProperty ;
+                 rdfs:domain s4ehaw:MeasurementFunction ;
+                 rdfs:range ssn-system:Precision ;
+                 rdfs:comment "Precision refers to the degree of reproducibility of a measured quantity (when the same quantity is measured several times how close are the measurements from each other), in percent."@en ;
+                 rdfs:label "precision"@en .
+
+
 ###  https://saref.etsi.org/saref4ehaw/presents
 s4ehaw:presents rdf:type owl:ObjectProperty ;
                 rdfs:domain saref:Service ;
@@ -761,14 +770,6 @@ s4ehaw:powerSourceType rdf:type owl:DatatypeProperty ;
                        rdfs:label "power source type"@en .
 
 
-###  https://saref.etsi.org/saref4ehaw/precision
-s4ehaw:precision rdf:type owl:DatatypeProperty ;
-                 rdfs:domain s4ehaw:MeasurementFunction ;
-                 rdfs:range xsd:float ;
-                 rdfs:comment "Precision refers to the degree of reproducibility of a measured quantity (when the same quantity is measured several times how close are the measurements from each other), in percent."@en ;
-                 rdfs:label "precision"@en .
-
-
 ###  https://saref.etsi.org/saref4ehaw/rechargeable
 s4ehaw:rechargeable rdf:type owl:DatatypeProperty ;
                     rdfs:domain s4ehaw:PowerSource ;
@@ -1216,6 +1217,10 @@ saref:Measurement rdf:type owl:Class .
 saref:NotifyCommand rdf:type owl:Class .
 
 
+###  http://www.w3.org/ns/ssn/systems/Precision
+ssn-system:Precision rdf:type owl:Class .
+
+
 ###  https://saref.etsi.org/saref/core/Property
 saref:Property rdf:type owl:Class .