HiddenBox
HiddenBox is a Process Field and it should be placed into a ProcessRecord Element.
<tr mo:type="ProcessRecord"> <td> <input type="hidden" name="pf_ID" value="{ID}" mo:name="ID" mo:type="HiddenBox" mo:field="true" mo:iValue="{ID}" /> </td> </tr>
See HiddenBox function class in MoreMotion Face API.