site HelloWorld
    origin: model.dbquity.com/examples
    version: 1.0.0
    description:
        "Hello World", says Dbquity.
        Illustrating site, class, invariant, area, and multiline.
    class Period
        description:
            This Period class comprises the Start, Days and End fields to
            capture an interval of a certain number of days starting and ending
            at certain dates.
            It uses the invariant property to declare the formula that ties
            together these three fields.
        date Start                  # initializes to today() by default
        integer Days
        date End
        # when a user changes one value, Dbquity seeks to update another as
        # needed to satisfy the invariant
        invariant:                                    
            Start + Days = End and Start <= End

    area Welcome
        Period Meeting
        text Greeting
            multiline
            placeholder:
                "type a few kind words here, please
                (you may use emojiis 👌)"