jQuery Grid Plugin - jqGrid

Hey Tony I've searched the forums and I can't seem to find an answer.

When I add or edit records hidden cols don't seem to get posted to the server.  Is there a way to turn that on or off?

so for example:

colMode:[

{name: 'Id', index:'id', width:50, hidden:true, editable: false, xmlmap: "Id"},

{name: 'Record Number', index:'RecordNum', width:50, hidden:true, editable: false, xmlmap: "RecordNum"},

{name: 'Project', index:''Project'', width:50, editable: true, xmlmap: "'Project'"},

etc..

But on the server I only get params:

ID=someId

Project=someProject

It's possible I don't need to be able to do this, but rather need to figure out someway to tie what shows up in the grid back to real data records in the database.  This is specifically to avoid creating new results every time the a edit is posted to the server.  Otherwise in the database the same record will be added over and over instead of being edited (or replaced).  If a row has or doesn't have a recordNum (say primary key) then I could tell that it already exists and could look up the values in the database.