Process All Fields

I've used a "process all fields" button successfully on a number of forms using this script or something similar to it:

for (var nPageCount = 0; nPageCount < xfa.host.numPages; nPageCount++) {
var oFields = xfa.layout.pageContent(nPageCount, "field");
var nNodesLength = oFields.length;

for (var nNodeCount = 0; nNodeCount < nNodesLength; nNodeCount++) {
oFields.item(nNodeCount).rawValue = ((oFields.item(nNodeCount).rawValue) * 2.54);
}
}

I would like help modifying this script so it only processes fields within a specific subform.

My thanks for any help.