I pass a URL in a hiden field but when I get the value on the server the "\" are not there and also some data is missing.

This is what I passe.

document.InitCommande.FileUrl.value="TPI\EST\02S\dwg\02S00C\02S00C3b\E1.tif"

This is What I get when I read the field.

TPIESTSdwgS00CS00C3bE1.tif 

Do I need to incode this string?