Need some sitemap help

[Katie_Venra]

For months now i have been manually putting in the lastmod date by editing the XML file inside my ftp program but i read somewhere (i think it was here in webmasterworld) that you can have the header of the http send the info instead...

The problem is, i dont know how to do it :(

Do i need to add a special line of code into the sitemap XML file?

[tedster]

Last modified is set for each specific url. Many automated sitemap generators can automatically grab the date from the server generated headers - I think this may be what you've read about.