Quote Originally Posted by Gerald C Koch View Post
It should be noted that the ISO standard which is used currently does not specify a special developer. It is left to the manufacturer to select one.
Indeed Ilford for example are explicit in this:- EXPOSURE RATING HP5 Plus has a speed rating of ISO 400/27 (400ASA, 27DIN, EI 400/27) to daylight. The ISO speed rating was measured using ILFORD ID-11 developer at 20oC/68oF with intermittent agitation in a spiral tank."

http://www.ilfordphoto.com/Webfiles/...1054152313.pdf