diff --git a/src/main/java/org/hbp/mip/model/Variable.java b/src/main/java/org/hbp/mip/model/Variable.java
index 08c8d97ff4c8ee4b43fd5182182bbdd2705bc53b..044cca2f772cfa00e519a4cfdd7156cf005b0f70 100644
--- a/src/main/java/org/hbp/mip/model/Variable.java
+++ b/src/main/java/org/hbp/mip/model/Variable.java
@@ -31,6 +31,7 @@ public class Variable {
     private Integer length = null;
     private Boolean isVariable = null;
     private Boolean isGrouping = null;
+    private Boolean isCovariable = null;
     private Boolean isFilter = null;
     @ManyToMany(fetch = FetchType.EAGER)
     private List<Value> values = new LinkedList<Value>();
@@ -142,6 +143,19 @@ public class Variable {
         this.isGrouping = isGrouping;
     }
 
+    /**
+     * Is it a co-variable ?
+     **/
+    @ApiModelProperty(value = "Is it a co-variable ?")
+    @JsonProperty("isCovariable")
+    public Boolean getIsCovariable() {
+        return isCovariable;
+    }
+
+    public void setIsCovariable(Boolean isCovariable) {
+        this.isCovariable = isCovariable;
+    }
+
     /**
      * Is it a filter ?
      **/
@@ -180,6 +194,7 @@ public class Variable {
         sb.append("  length: ").append(length).append("\n");
         sb.append("  isVariable: ").append(isVariable).append("\n");
         sb.append("  isGrouping: ").append(isGrouping).append("\n");
+        sb.append("  isGrouping: ").append(isCovariable).append("\n");
         sb.append("  isFilter: ").append(isFilter).append("\n");
         sb.append("  values: ").append(values).append("\n");
         sb.append("}\n");