After the words 1. sāyaṃ 'at eve' 2. ciram 'for a long time' 3. prāhṇe 'in the forenoon' 4. prage 'at dawn' and after indeclinables expressing time, there are the affixes ṭyu and ṭyul and their augment is tuṭ,
The word कालात् is understood here also. Thus सायं + ट्यु = सायं + तुट् + ट्यु = सायंतनम् (VII. I. 1) 'belonging to the evening'. चिरंतनम्, 'lasting', प्राह्णेतनम् 'what is of the forenoon', प्रागेतनम् \what is of the early morn\.
The word सायं is a word ending in म् and is an Indeclinable. These affixes would also come by virtue of its being an indeclinable, after that सायं ॥ The present सायं is derived from the root से by adding the affix घञ् ॥ It always ends in म् when these affixes are added. The word चिरं always ends in म् ॥ प्राह्णे and प्रगे always end in ए ॥
As regards Indeclinables, the examples are दोषातनम् 'belonging to the night'. दिवातनम् 'belonging to the day'.
Vart:- The affix त्न comes after the words चिर, परुत् and परारि ॥ As चिरत्नम्, परुत्नम्, and परारित्नम् ॥
Vart:- The ग of प्रग in elided in the Chhandas before this affix त्न. as, प्रत्नम् ॥
Vart:- The affix डिमच् comes after अग्र, आदि and पश्चाद्; as, अग्रिमम्, आदिमम् and पश्चिमम् ॥
Vart:- So also after अन्त, as, अन्तिमम् ॥
The defference between tyu and tyul is in accent, Thus सायन्त꣡न and साय꣡न्तन, चिरन्त꣡न and चिर꣡न्तन, प्राह्णेत꣡न and प्राह्णे꣡तन, प्रगेत꣡न, प्रगे꣡तन, दिवात꣡न and दिवा꣡तन, दोषात꣡न and दोषा꣡तन ॥,