The shortening of the penultimate of the stem, before the causative affix in the reduplicated Aorist, does not take place, when it is a (Denominative) aṅga (stem), which has lost a simple (end vowel of the Nominal stem) before the Causative sign and also not, when it is the verb śās , or a root which has an indicatory ṛ,
The word अग्लोपिन् means literally a stem, in which a simple vowel (अक् pratyahara) or a portion containing an अक् vowel has been dropped. As the final vowels of Denominative stems are so elided before the Causative sign णि, the sutra has been translated accordingly. Thus अममालत् = मालामाख्यत्; अममातरत् = मातरमाख्यत्, अत्यरराजत् = राजानमतिक्रान्तवान्, अन्वलुलामत् = लोमान्यनुमृष्टवान् ॥ Where a simple अक् vowel alone is elided, as in the case of माला, there the elided आ being sthanivat, would prevent the shortening, the आ of मा not being then considered penultimate. So that अग्लोपिन् could be spared from the sutra, since the sthanivad-bhava would prevent shortening. But where an अक् vowel plus a consonant is dropped, as in राजन् and लोमन्, there the sthanivad-bhava does not apply (I. I. 57), hence the necessity of employing the term अग्लोपिन् in the sutra. Similarly अशशासत् with शास्; and अबबाधत् from बाधृ, अययाचत् from याचृ, and अडुढौकत् from ढौकृ ॥ See (III. I. 21) and (III 1. 25).,