/aN / अण्

The /pratyAhAra /aN means

a i uN अ इ उण् — see /zivasUtra

namely

a A i I u U अ आ इ ई उ ऊ by aNuditsav...,

except in sUtra aNuditsav..., where it means

a i uN अ इ उण्
R Lk ऋ ऌक्
e oG ए ओङ्
ai auc ऐ औच्
ha ya va raT ह य व रट्
laN लण्

namely

a A i I u U R RR L e o ai au h y v r l अ आ इ ई उ ऊ ऋ ॠ ऌ ए ओ ऐ औ ह्य्व्र्ल्.

/aN can have two meanings because N ण् appears in two places at the /zivasUtra.

See also /aN' (/kRt affix) and /aN'' (/taddhita affix).

How do we know that the aN अण् mentioned the sUtra aNuditsav... is meant to stop at laN लण्, and the aN अण् in all other sUtras stops at uN उण्? Because if we choose otherwise, very unpleasant things start to happen. pANini पाणिनि is okay with ambiguity, as long as it can be sorted out somehow.