JqGrid documentation states the following regarding postData:
an array used to add content to the data posted to the server
And that's it. So, I'm using postData to send a variable to my PHP so that I can use a switch case to call the function I want.
This allows me to have a single PHP page containing all the functions for my project. I want to do the same thing with editData so I don't need a PHP page for every inline editing function associated with the project. 
However, editData doesn't seem to be passing to the PHP page. I tried printing the POSTed variables to a file and they were empty. Suggestions?
Note: I am aware of the editData bug, but this should have been fixed by version 4.4.4 which is the one I'm using    
$("#list").jqGrid({
    url:'functions.php',
    datatype:'xml',
    mtype:'POST',           
    postData: { 
        action:'popGrid', 
        sqlCount:sqlCount, 
        sqlSelect:sqlSelect, 
        sqlSelect2:sqlSelect2, 
        label1:label1, 
        label2:label2,
    },
    colNames:['Label','Account_Num','Amount', 'Type Code', 'Record Code',    'Sequence'],
    colModel :[
        {name:'label', index:'label', width:150, align:'center', sortable:false, editable:true},
        {name:'cntrct_id', index:'cntrct_id', width:150, align:'center', sortable:true},
        {name:'amount', index:'amount', width:150, align:'center', sortable:false, editable:true},
        {name:'type_cd', index:'type_cd', width:150, align:'center', sortable:false, editable:true},
        {name:'rec_cd', index:'rec_cd', width:150, align:'center', sortable:false},
        {name:'db_seq', index:'db_seq', width:150, align:'center', sortable:false},
    ],
    editurl: 'functions.php',
    extraparam: { action: function(){ return 'grdAdjust'; } },
    onSelectRow: function(id) {
        if(id && id!==lastSel) {
            jQuery('#list').restoreRow(lastSel);
            jQuery('#list').editRow(id,true);
            lastSel=id;
        }
    },
    pager: '#pager',
    rowNum:100,
    rowList:[100,200,300,400,500,600,700,800,900,1000],
    sortname: 'cntrct_id',
    sortorder: 'desc',
    viewrecords: true,
    caption: 'Adjustments'
});