Macro to produce a hidden form field for the users session ID
Tag expansion example
<input type="hidden" name="mv_session_id" value="abc123">
All HTML forms must include a hidden
"mv_session_id" input variable to allow for users who cannot accept session cookies
for one reason or another.
This tag outputs an appropriate "<input>" HTML tag
whenever a non-cookie-accepting visitor is detected.
If the user is using a session cookie then this tag will not return
anything at all.
This tag was introduced in version 5.4.0,
and is therefore not available for use with any earlier Interchange version.