The following is part of a form I am setting up

<INPUT TYPE="radio" NAME="subjct" VALUE="Floral">Floral <BR>
<INPUT TYPE="radio" NAME="subjct" VALUE="Landscape">Landscape <BR>
<INPUT TYPE="radio" NAME="subjct" VALUE="Abstract">Abstract <br>
<INPUT TYPE="radio" NAME="subjct" VALUE="Life">Life<br>
<INPUT TYPE="radio" NAME="subjct" VALUE="Varied">Varied <br>
Other:....
<INPUT TYPE="radio" NAME="subjct" ><INPUT TYPE="text" NAME="other_subject" size="20">

I have also got the following
<input type=hidden name="required" value="surname,firstname,city,country,email,media,subjct,imageurl">
to check that required info is given.

Is there a way to force the form to require the text NAME="other_subject" when the radio box in front of it is checked or alternatively if I drop the radio box from in front of the text box how can I require either the one of the other radio boxes above or the text to be completed?

If it would uncomplicate this to see the form a test form is at
http://artistwebgallery.com/app_form.html