Pañcaviṃśa (Tāṇḍya Mahā) Brāhmaṇa 10.11.1

10.11.1

dravadiḍaṃ prathamasyāhno rūpam iḍāvibhakter ūrdhveḍaṃ dvitīyasya pariṣṭubdheḍaṃ tṛtīyasyeḍābhir aiḍaṃ caturthasyādhyardheḍaṃ pañcamasya yad ihākāreṇābhyastaṃ tat ṣaṣṭhasyāhno rūpam iḍānāṃ yasmād eṣā samānā satīḍāvibhaktir nnānārūpā tasmāt samānāḥ santaḥ paśavo nānārūpāḥ

A flowing iḍā is the characteristic mark of the first day among the variations of the iḍā; an upward iḍā is of the second; an iḍā surrounded by stobhas is of the third; an iḍā with iḍās is of the fourth; an iḍā with one and a half is of the fifth; that which is repeated with the word ihā is the characteristic mark of the sixth day among iḍās. Because this distribution of the iḍā, though uniform, is manifold in form, therefore cattle, though being uniform, are manifold in form.