An affix -- prāgdīvyato'ṇ [[4.1.83]] etc. comes after a word in the Instrumental -3rd case in construction in the sense of 'in the same direction with that'.,
The word एक दिक means तुल्य दिक i.e. a common direction. Thus सुदाम्ना एकदिक = सौदामनी विद्युत् \a lightening, literally that which is in the same direction as the hill called the Sudaman.\ So हैमवती, त्त्रैककुदी, पैलुमूली ॥
The repetition of तेन, though it could have been supplied by anuvritti from 4.3.101, is for the sake of indicating that the anuvritti of the छन्दस् which regulated all the preceding ten sutras, does not extend to this aphorism, and therefore the तद्विषयता of 4.2.66 which was applied in those sutras does not apply here.,