SitePageData.cs

public abstract class SitePageData : PageData, ICustomCssInContentArea, ICarouselContent
{

    // ...
    
    [Display(GroupName = "CarouselContent", Order = 10)]
    [CultureSpecific]
    [UIHint(UIHint.Image)]
    public virtual Url Image { get; set; }

    [Display(GroupName = "CarouselContent", Order = 20)]
    [CultureSpecific]
    public virtual string ImageDescription
    {
        get
        {
            var propertyValue = this["ImageDescription"] as string;
            return string.IsNullOrWhiteSpace(propertyValue) ? Heading : propertyValue;
        }
        set { this["ImageDescription"] = value; }
    }

    [Display(GroupName = "CarouselContent", Order = 30)]
    [CultureSpecific]
    public virtual string Heading { get; set; }

    [Display(GroupName = "CarouselContent", Order = 40)]
    [CultureSpecific]
    [UIHint(UIHint.Textarea)]
    public virtual string SubHeading { get; set; }

    [Display(GroupName = "CarouselContent", Order = 50)]
    [CultureSpecific]
    public virtual string ButtonText { get; set; }

    [Display(GroupName = "CarouselContent", Order = 60)]
    [CultureSpecific]
    public virtual Url ButtonLink { get; set; }

    [Ignore]
    public bool Selected { get; set; }

    // ...
}