A field name that people using the embedded template editor can choose from, with the data type and settings a field gets when it's given that name.
@type t() :: %Docspring.Model.PredefinedField{ display_name: String.t() | nil, field_required: boolean() | nil, name: String.t(), option_list: String.t() | nil, required_in_template: boolean() | nil, title: String.t() | nil, type: Docspring.Model.FieldType.t() }