Importing UTF-8 Text

I am using doc.Import to import a text file into FrameMaker. The text file is encoded in UTF-8. Is there a UTF-8 Constant for importing text files in FrameMaker? Here is my function:

TTC_MB.importFile = function (filename, textLoc, doc) {
    
    var importProps, retProps, i;
    
    // Get default property list for importing documents.
    importProps = GetImportDefaultParams ();
    // Get a property list to return any error messages.
    retProps = new PropVals ();

    // Set specific import property values to import the document.
    i = GetPropIndex (importProps, Constants.FS_AlertUserAboutFailure);
    importProps[i].propVal.ival = false;
    i = GetPropIndex (importProps, Constants.FS_HowToImport);
    importProps[i].propVal.ival = Constants.FV_DoByCopy;

    // Attempt to import the document.
    doc.Import (textLoc, filename, importProps, retProps);
};