abstract class Field extends ContentUnit {
  attr boolean[1] required;
}

@gmf.node(label="name", figure="rectangle", label.icon="false", label.pattern="{0} :' Text'", label.edit.pattern="{0}")
class TextField extends Field {
  attr int displaySize;
  attr int maxLength;
}

@gmf.node(label="name")
class ContentType extends ContentUnit {
  attr String group;
  @gmf.compartment(layout="list", collapsible="false")
  ref Field[*] field;
}