<interp> (interpretazione) riassume una specifica annotazione interpretativa che può essere
associata ad una porzione di testo [18.3 Spans and Interpretations]
Generally, each interp element carries an xml:id attribute. This permits the encoder to explicitly associate the interpretation represented
by the content of an interp with any textual element through its ana attribute.
Alternatively (or, in addition) an interp may carry an inst attribute that points to one or more textual elements to which the analysis represented
by the content of the interp applies.