<?php
is_uploaded_file($_FILES['data_file']['tmp_name'])  // true

$test = $_FILES['data_file']['tmp_name'];
is_uploaded_file($test)  // true

// Trying to do a multi-stage form with a confirmation page.
// On the confirmation page, have this.
<input type="text" name="tmp_name" value="<?php echo $_FILES['data_file']['tmp_name']; ?>">

// Then when submitted:
is_uploaded_file($_POST['tmp_name']) // FALSE

// This always evaluates to FALSE even though the paths are IDENTICAL Why???
?>