Optionally when the compound denotes a condition or an instrument, the n of pāna is changed to ṇa , when it is a second member, the cause of change occurring in the first member in a compound.,
Thus क्षीरपाणम् or क्षीरपानम् \drinking of milk\ कषायपानम् or कषायपाणम् 'drinking of kashaya'. सुरापाणम् or सुरापानम् &c are examples of भाव or condition.
Similarly क्षीरपाणः of क्षीरपानः कंसः 'a vessel for drinking milk'. This is an example of करण or instrument.
Vart:- Optionally so in the case of गिरिनदी &c. Thus गिरिनदी or गिरिणदी; चक्रनदी or चक्रणदी, चक्रनितम्बा or चक्रणितम्बा ॥,