control editor input format

Hi All,

I am new to editor, here is a simple question, how to control the text input max length, I can not seem to find a document to mention this.

What I want is:

                   {
	                "label": "Code:",
	                "name": "code",
                        "type": "text",
                        "maxLength": "4"
	            }

is there a maxlength attribute available?

Thanks a lot.

Tiger