The affixes yat (yaṃ) and kha (īna) come in the sense of 'who is fit or able to follow' after the word adhvan,
Thus अध्वानमलंगामी = अध्वनीनः or अध्वन्यः 'able to undertake a journey'. By aphorisms 6.4.168, 6.4.169, the word अध्वन् retains its original form before the affix य and ख, not losing its final अन् which it does before other affixes, by 6.4.144.,