Add to ORKGwelcomes letters commenting on papers published in the journal in the previous six months. Topics not related to papers published earlier in the journal may be introduced as a letter: letters reporting original data may be sent for peer review. Presentation Letters should be: + not more than 600 words and six references in length + typed in double spacing (fax copies and paper copy only) + signed by all authors They may contain short tables or a small figure. Please send a copy of your letter o