Before the affixes 1. sya (First future and Conditional) 2. sic (S-Aorist) 3. sīyud (Benedictive) and 4. tāsi (Periphrastic Future), when they are used in the bhāva (Impersonal) and karma (Passive) voices 1. the verbal stems ending in a vowel in the Grammatical system of instruction (upadeśa), as well as the verbs 2. han 'to kill' 3. grah 'to seize' and 4. dṛś 'to see' are treated optionally in the same way as in the 3rd Person of the Passive Aorist in ciṇ and when so treated, they have the augment iṭ ,
The augment इट् is, of course, added to the affixes and स्व, सिच्, सीयुट् and तासि and not to the stem. What are the special objects served by this atidesa aphorism? They are given in the following verse :-
Karika
चिण्वद् वृद्धिर्युक् च हन्तेश्च घत्वं
दीर्घश्चोक्तो यो मितां चिणीति ।
इट् चासिद्धस्तेन मे लुप्यते णि-
र्नित्यश्चायं वलनिमित्तोऽविघाती ॥
First :-The Vriddhi takes place as in चिण् 7.2.116, 7.3.34, secondly, there is the addition of युक् augment 7.3.33, thirdly घ is substituted for the ह of हन् 7.3.54, fourthly, the roots having indicatory म् (Bhuadi 809 to 873) optionally lengthen their vowel 6.4.93, and lastly the addition of the augment इट् being considered as asiddha or not to have taken effect by 6.4.22, the rule 6.4.51 applies and the causative affix णि is elided : and this इट् is added irrespective of the conditions and limitations of 7.2.35 &c.
(1) Roots ending in a vowel in the Dhatupatha with the affix स्य as, चि :-चायिष्यत or चेष्यते, अचायिष्यत or अचेष्यत ॥ So also with दा, as, दायिष्यते or दास्यते, अदायिष्यत or अदास्यत ॥
In शमि there are three forms, the two शामिष्यते or शमिष्यते, अशामिष्यत and अशमिष्यत being given by the elision of the causative ending by 6.4.51, in spite of the इट् augment which is considered as asiddha : and शम् being a root of मित् class, the अ is lengthened optionally by 6.4.93. The forms शमयिष्यते and अशमयिष्यत are given when not treated as चिण्, the causative is retained, the penultimate being shortened by 6.4.92. With the affix सिच् -अचायिषाताम्, or अचेषाताम्, अदायिषाताम्, or अदिषाताम् and अशामिषाताम् or अशमिषाताम् ॥ With the affix सीयुट् - चायिषीष्ट or चेषीष्ट, दायिषीष्ट or दासीष्ट and शामिषीष्ट or शमिषीष्ट ॥ With the affix तासि :- चायिता or चेता, दायिता or दाता, शामिता or शमिता ॥ The चिण् aorist model of these roots is अचायि, अदायि 7.3.33, and अशमि 7.3.34 or अशामि 6.4.93.
(2) हन् :- Fut. घानिष्यते or हनिष्यते; Con. अघानिष्यत or अहनिष्यत, Aor. अघानिषाताम् or अवधिषाताम् and अहसाताम् 2.4.44; Ben घानिषीष्ट or वधिषीष्ट; Per. Fut. घामिता or हन्ता ॥ The चिण् model is अघानि ॥
(3) ग्रह :- Fut. ग्राहिष्यते or ग्रहीष्यते Con. अग्राहिष्यत or अग्रहीष्यत; Aor. अग्राहिषाताम् or अग्रहीषाताम् (अग्रहिषाताम)?; Ben. ग्राहिषीष्ट or (ग्रहिषीष्ट) पहीषीट, Per. Fut. ग्राहिता or ग्रहिता ॥ The lengthening of ही takes place by 7.2.37. The चिण् model is अग्राहि ॥
(4) दृश् :- Fut. दर्शिष्यते or द्रक्ष्यते, Con. अदर्शिष्यत or अद्रक्ष्यत; Aor. अदर्शिषाताम् or अदृक्षाताम् ; Ben दर्शिषीष्ट or द्रक्षीष्ट; Per. Fut. दर्शिता or द्रष्टा (दर्ष्टा)?॥ The चिण् model is अदर्शि ॥
Why do we say before स्य &c? Observe चेतव्यम्, दातव्यम् ॥ Why in the Impersonal and Passive ? Observe चेष्यते and दास्यते ॥ Why in Upadesa ? The rule applies to कारिष्यते also, though कार् (after guna change) ends in a consonant, but in its original ennuciation it ends with a vowel. The atidesa rule being enunciated with regard to stems (anga), prevents the substitutions of हन् and इङ् and इण् ॥ Thus हनिष्यते, घानिष्यते, एष्यते or आयिष्यते, अध्येष्यते or अध्यायिष्यते ॥ The substitutes वध or गा 2.4.42, 2.4.43, 2.4.45, 2.4.50 do not come according to the Kasika, when these roots are treated as चिण् ॥,