diff -r 1a0bed0b4f1c -r 1cb8f90bf4fd svghmi/widget_assign.ysl2
--- a/svghmi/widget_assign.ysl2	Fri Apr 05 14:55:58 2024 +0200
+++ b/svghmi/widget_assign.ysl2	Fri Apr 05 14:59:00 2024 +0200
@@ -71,7 +71,7 @@
         const "name","substring-before(@value,'=')";
         const "value","substring-after(@value,'=')";
         const "index" foreach "$paths" if "@assign = $name" value "position()-1";
-        const "isVarName", "regexp:test($value,'^[a-zA-Z_][a-zA-Z0-9_]+$')";
+        const "isVarName", "regexp:test($value,'^[a-zA-Z_][a-zA-Z0-9_]*$')";
         choose {
             when "$isVarName"{
     |         const «$value» = this.assignments["«$value»"];