A URI referring to a document may optionally include a fragment identifier suffix. This is the portion of the URI following the # symbol. A fragment identifier on the end of a URI refines the scope of the URIs reference to just a part of the larger information resource which the URI refers to. A fragment id might refer to an element or set of elements in an XML document; a rectangle within an image; or a specific sequence of frames within a video file. Because different types of media can be fragmented in various ways, each media type is associated with a particular syntax for fragment identifiers.