The NISO STS Tag Sets contain several elements that describe and point to non-XML material: <graphic>, <inline-graphic>, <media>, <supplementary-material>, and <inline-supplementary-material>. The elements <graphic> and <inline-graphic> contain a pointer to a still image (such as a photograph, diagram, line drawing, etc.) that is part of the document. The element <media> contains a pointer to a non-XML, frequently binary, object (such as a movie, audio clip, dataset, or other non-XML format) that is integral to the document’s content, where  “integral” means that the media object is discussed within (and possibly displayed within) the document; the media object is part of the document.

In contrast, the elements <supplementary-material> and <inline-supplementary-material> are used to describe either XML material (such as figures, tables, and sections) or non-XML material (such as graphics, films, audio clips, datasets, or other material) that are considered to be “additional material” (non-integral) accompanying a document. Like <graphic>, <inline-graphic>, and <media>, the supplementary material elements never contain the object they describe, even if it is an XML object such as a figure, although they may point to it.

The element <inline-supplementary-material> is used to mark up a reference to additional material, where the reference appears within the regular flow of the text and does not have a preview image or separate caption. The <supplementary-material> element is used to describe a more complicated reference, where the description of the supplementary object resembles a figure in that it can be positioned as a floating or anchored object and may take a caption.