Māṇḍūkī Śikṣā 57

57

svaritaprabhavaṃ pracitātsvaritameva udāttaṃ vā
anudāttameva taṃ vidyādṛtaṃ ca tadviddhi yatpracitam

Arising from the circumflex accent, from the monotone accent, either as circumflex accent or acute accent, / one should know that as grave accent alone; and know that which is monotone accent as proper.