This paper is based on all text received since the conference was announced late in 2009. Prospective participants were informed that no individual papers were expected but that the conference would be structured around one document, baptized ‘Lead-paper’, that would go through several rounds of amendments, additions, criticisms and alterations in the months ahead, aiming at a discussion document that would already represent views of participants and would allow us to begin our conference with a common knowledge based on our exchange of data, views, and questions, making the conference the more fruitful. This proposition led to a 1st version of the Lead-paper (5 pages, 2000 words) December 30, 2009, going through a 2nd edition (31 January 2010, 12 pages, 5152 words), a 3rd edition (1 March, 50 pages, 17.850 words) and a 4th edition (70 pages plus 14 pages attachments, 29.777 words), e-mailed on March 26, 2010, to all participants and distributed in Deventer at the opening session on 8 April 2010 in print. This 4th edition ‘Lead-paper’ was used as the substantial agenda for the conference on 8-9 April 2010 in Deventer. This is the 5th edition which incorporates substantial thoughts, criticism, questions, and remarks contributed in writing, by the participants and from other sources.