ImGearMetadataHead is a special kind of metadata node with a null Parent field and not more than one child. It is present in every instance of ImGearPage class and ImGearDocument class as class member.

If the page or document has metadata, an instance of ImGearMetadataTree class is attached to the head as a child node. Otherwise, child is null.

ImGearMetadataHead may only be the root of metadata tree. Attempting to attach this class to any node causes ImageGear to throw an exception.