To create a validation warning or a dependency when there is no data entered in a field, you can use a calculation field to check if any data is entered. See ‘ Forcing Castor to calculate with empty fields’ for more information on empty fields.

The below calculation will check for empty or ‘NA’ values within a field.

'##allowempty##';
if("{Variable}" == "'NA'" || "{Variable}" == ""){
 "Nothing filled in";
} else {
 "Variable is filled in";
} 

To use the above code replace ‘Variable’ with your own variable names. If you want to create a validation message, you can set a validation on this calculation field. If you want to create a dependency, refer to the calculation field in your dependency.