From In-Portal User Manual

The Form Field add/edit form contains the following fields:

• Field name – internal field name
• Field label – the language label used on the front end for displaying the field prompt. You may enter the language label name here and create the language label for every language in use through Configuration -> Regional section. If your site is not multilingual and you are not planning on adding more languages, you may simply enter the field prompt directly by prefixing it with + sign, for example you may enter “+Your Name” (or, for the multilanguage option, “form_YourName” and create a corresponding language label)
• Field prompt – same as Field label, but used on the administrative console, you may also enter language label name or direct value prefixed by + sign into this field. In most of cases this field should contain the same value as the Field label
• Input type – drop down for selecting the input type of the field. This option defines how the field will look like on the form. The Drop-down and Radio buttons types require entering List of Values (see below)
• Validation – this option controls how the entered value should be validated. Currently it supports only e-mail address validation.
• List of Values – in combination with Drop-down and Radio button input types this is used for listing the possible values of the field. It accepts comma-separated pairs of key=value, where key is the internal reference of the value and the value is the value name, presented in the drop-down or next to the radio button, respectively. The value is interpreted as a language label, unless it starts with + sign. For example, if your form should ask for a day of week, you may enter the following list of values:
  
  1=+Sunday,2=+Monday,3=+Tuesday,4=+Wednesday,5=+Thursday,6=+Friday,7=+Saturday
  
  If you would like the first option to be empty (for the drop-down type), simply start the list with “=+,”
  This field is also used with Textarea input type for specifying textarea options. For example, you may specify:
  
  cols=”60” rows=”5”
  
  for the textarea to be 60-characters wide and have 5 lines.
• Default value – the value of the field, pre-populated when user opens the form. For the fields with lists of values, this field should contain the key part of key=value pair.
• Priority – the priority or the display order of the field on the form.
• Required – controls if the field is required to fill in for submitting the form
• Display in grid – controls if the field should be displayed in the form submissions list, or only when viewing single submission details
• Is System – if set to on, the field will not be displayed on the front end. Make sure not to set the system field as required, because in this case the form can’t be submitted