Definition: alphabet: traditional enumeration of phonetically independent letters generally beginning with the vowel a (अ). Although the number of letters and the order in which they are stated differ in different treatises, still, qualitatively they are much the same. The Śivasūtras, on which Pāṇini's grammar is based, enumerate 9 vowels, 4 semi-vowels, twenty five class-consonants and 4 | sibilants. The nine vowels are five simple vowels or monothongs (समानाक्षर) as they are called in ancient treatises, and the four diphthongs, (सन्ध्यक्षर). The four semi-vowels y, v, r, l, (य् व् र् ल्) or antasthāvarṇa, the twenty five class-consonants or mutes called sparśa, and the four ūṣman letters ś, ṣ, s and h (श् ष् स् ह्) are the same in all the Prātiśākhya and grammar works although in the Prātiśākhya works the semi-vowels are mentioned after the class consonants.The difference in numbers, as noticed, for example in the maximum number which reaches 65 in the VājasaneyiPrātiśākhya, is due to the separate mention of the long and protracted vowels as also to the inclusion of the Ayogavāha letters, and their number. The Ayogavāha letters are anusvāra, visarjanīya,jihvāmulīya, upadhmānīya, nāsikya, four yamas and svarabhaktī. The Ṛk Prātiśākhya does not mention l (लृ), but adding long ā (अा) i (ई) ，ū (ऊ) and ṛ (ऋ) to the short vowels, mentions 12 vowels, and mentioning 3 Ayogavāhas (< क्, = प् and अं) lays down 48 letters. The Ṛk Tantra Prātiśākhya adds the vowel l (लृ) (short as also long) and mentions 14 vowels, 4 semivowels, 25 mutes, 4 sibilants and by adding 10 ayogavāhas viz. 4 yamas, nāsikya, visarjanīya, jihvāmulīya, upadhmānīya and two kinds of anusvāra, and thus brings the total number to 57. The Ṛk Tantra makes a separate enumeration by putting diphthongs first, long vowles afterwards and short vowels still afterwards, and puts semi-vowels first before mutes, for purposes of framing brief terms or pratyāhāras. This enumeration is called varṇopadeśa in contrast with the other one which is called varṇoddeśa. The Taittirīya prātiśākhya adds protracted vowels and lays down 60 letters : The Ṣikṣā of Pāṇini lays down 63 or 64 letters, while the Vājasaneyi-prātiśākhya gives 65 letters. cf. V. Pr. VIII. 1-25. The alphabet of the modern Indian Languages is based on the Varṇasamāmnāya given in the Vājasaneyi-prātiśākhya. The Prātiśākhyas call this enumeration by the name Varṇa-samāmnāya. The Ṛk tantra uses the terms Akṣara samāmnāya and Brahmarāśi which are picked up later on by Patañjali.cf. सोयमक्षरसमाम्नायो वाक्समाम्नायः पुष्पितः फलितश्चन्द्रतारकवत् प्रतिमण्डितो वेदितव्यो ब्रह्मराशिः । सर्ववेदपुण्यफलावाप्तिश्चास्य ज्ञाने भवति । मातापितरौ चास्य स्वर्गे लोके महीयेते । M. Bh. Ahnika.2-end.