diff --git a/src/section/section_type.ts b/src/section/section_type.ts
index 5a6a944f57db7700d756031c07652654db30298b..25b540edb6ab5b11a78520405956e876f54f2a87 100644
--- a/src/section/section_type.ts
+++ b/src/section/section_type.ts
@@ -21,7 +21,7 @@ export abstract class cParamsCanal extends ParamsEquation {
                 super();
                 this._Ks = new ParamDefinition(nodeType, 'Ks', ParamDomainValue.POS, rKs);
                 this._Q = new ParamDefinition(nodeType, 'Q', ParamDomainValue.POS_NULL, rQ);
-                this._If = new ParamDefinition(nodeType, 'If', ParamDomainValue.ANY, rIf);
+                this._If = new ParamDefinition(nodeType, 'If', ParamDomainValue.POS, rIf);
                 this._Prec = new ParamDefinition(nodeType, 'Prec', ParamDomainValue.POS, rPrec);
                 this._iPrec = new ParamDefinition(nodeType, 'iPrec', ParamDomainValue.ANY, Math.round(-Math.log(rPrec) / Math.log(10)));
                 this._YB = new ParamDefinition(nodeType, 'YB', ParamDomainValue.POS, rYB);