Dear Roger
as mentioned: i haven't had the chance in the past to use the identifier" option to deal with such a type of demand. But you can assign a "document" (e.g.graphic) to an identifier and therefore you should be able to "print" it using WWI procedures.
May be check: http://www.se80.co.uk/saptables/e/estr/estri.htm
Here you can clearly see, that ESTRI contains option to have a reference to a DMS key (e.g. BMP file. jpg file etc.)
Hope this helps
C.B.