Sending null/blank value for variable

[Don Howell]

I frequently fill forms where the values change every time. 

I find the easiest way to do this is to set a variable in the form field rule, and then use a local script to generate a list of the variables and values, which I paste into the Autofill variables to use across multiple profiles.

 I cannot seem to figure out how to send a blank value. If I delete the variable or do not enter one, it sends the bracket notation i.e. {@variable} instead. 

Is there a value I can assign to the variable which will leave it blank in the form?