In the remaining cases where (ā or ya is not substituted) there is elision of the final yuṣmad and asmad,
This elision finds scope in the Singular and Plural of the Ablative, Dative, Genitive, and the Nominative. Thus त्वम्, अहम्, यूयम्, वयम्, तुभ्यम्, मह्यम्, युष्मभ्यम्, अस्मभ्यम्, त्वत्, मत्, युष्मत्, अस्मत्, तव, मम, युष्माकम्, अस्माकम् ॥ The following sloka gives the cases which are included in the word शेषः :-
पञ्चम्याश्च चतुर्थ्याश्च षष्ठीप्रथमयोरपि ।
यान्यद्विवचनान्यत्र तेषु लोपो विधीयते ॥
The word शेष is employed in the sutra for the sake of clearness. For there will be elision universally before all case-affixes. This is the general rule. To this there is the exception that before non-substitute case-affixes there will be य 7.2.89. To this latter, there is an exception that before non-substitute case-endings beginning with a consonant, आ comes. Thus without any confusion, the आ, the य, and the lopa find their respective scopes.
When there is elision, why is not टाप् added in the Feminine; in त्वं ब्राह्मणी; अहं ब्राह्मणी ? The टाप् is not added on the maxim सन्निपात लक्षणो विधिरनिमित्तं तद्विघातस्य 'a rule which is occasioned by a certain combination, does not become the cause of the destruction of that combination.' Because the ending in अ of युष्मद् and अस्मद् was occasioned by vibhakti combination, if this latter occasion टाप्, then it will destroy its own fruit.
Or the words युष्मद् and अस्मद् may be taken to have no gender, and equally applicable to both masculine and feminine.
In order to avoid all this difficulty about टाप् some would elide the अद् (or टि portion) of युष्मद् and अस्मद् under this sutra. They argue that by the next sutra 7.2.91, the portions 'yushm' and 'asm', namely the portions upto म् of युष्मद् and अस्मद् are replaced by substitutes. The portion that remains (शेष) is अद्, and it is this अद् which is to be elided.
Why is this 'lopa' taught again, when by 7.2.102, all त्यदादि pronouns have अ substituted for their finals before case-endings; and so would yushmad and asmad, lose their finals and become yushma and asma by that rule? That rule does not apply to yushmad and asmad, because by an ishti that rule is restricted to tyadadi pronouns upto द्वि, thus excluding युष्मद्, अस्मद्, भवतु and किम् ॥,