Dave Just after sending a reply to the piclist regarding your posting, I discovered that the email address of Herve Cousin, the author of this excellent altimeter web page. I suggest you contact Herve Cousin and ask him for the URL of his web page. Its really worth it to look at. Rgds Werner -- Werner Terreblanche http://www.aztec.co.za/users/werner wterreb@plessey.co.za (work) OR werner@aztec.co.za (home) Plessey SA, PO Box 30451,Tokai 7966, Cape Town, South Africa or at home : Suite 251, PostNet X5061, Stellenbosch, 7599 Tel +27 21 7102251 Fax +27 21 7102886 Home +27 21 8872196 ------------------------------------------------------------