UFT learns source index and automatic xpath of an object automatically, if configured. These object identification properties are not visible in the object repository; hence users cannot edit or modify them. During test run, UFT uses these properties first to locate the object in UI.
Source Index is a zero based integer value which represents the position of the element among all elements in HTML document. UFT learns this property automatically when learning the object description. However, this property is hidden in object repository; hence, users cannot edit or modify the value of this description property.