Remi, when you tar zxvf the openacs tarball, you will find a directory some what like this: openacs_versionnum/www/doc/sql.. there are lots of *.sql files in there.. that's where the datamodem is.. if you want some explanation of how these models are being used.. you should read Philip and Alex's Guide to Web Publishing (you can learn about it at www.arsdigita.com/asj).. also.. usually there's documentation for all the modules being used in ACS.. these docs are in HTML format and contained in openacs_versionnum/www/doc.. And even more importantly.. if you are lost with the SQL or TCL scripts.. you are more than welcome to express your puzzlement here on the OpenACS Development Discussion Forums or at Philip Greenspun's Web Tool Reviews Web/DB and Java Forums (on www.arsdigita.com/asj)...