What is the syntax for values in the "constraint" field of the XLM form? I am putting in "<1000" so as to limit inputs to have 3 or less characters and it errors out on me.
The constraint needs to include the field that you want to compare against (i.e., what is less than 1000?). From the context of your question, it sounds like you want to control the size of the field with the constraint, so you can use . to represent your field: