When you post your form use the method below:
<anchor>post<go sendreferer=true href="test.wml"></go></anchor>

the Browser will add a parameter to Request Head named "REFERER"
REFERER is the URL of currently page, if you set sendreferer as true,the next page can check the URL that the post page!

Who can change the "REFERER" in Request Head to any URL you want when you post your form that sendreferer is true