A Photo has properties of title, image, description, classification (photoClassification), date taken, date submitted, subject location o s (gridref), subject location w g s (latlong), photographer location o s (gridref) and view direction (direction). A Photo must be had by one GridSquare. A Photo must have one Category. A Photo must be had by one Contributor.
A GridSquare has properties of gridref (gridref). A GridSquare may have many Photos. A GridSquare may have many Comments.
A Category has properties of name. A Category may be had by many Photos.
A Contributor has properties of name, nickname, email, possibly website, home location (gridref) and date joined. A Contributor may have many Photos. A Contributor may have many Comments.
A Comment has properties of text and date submitted. A Comment must be had by one GridSquare. A Comment must be had by one Contributor.