A word ending with the Locative -7th-case-affix is compounded with words ending with kṛtya-affix (a Future Passive Participle) and the resulting compound is tat-puruṣa ,
This compound is confined to the words formed by the kritya affix यत् and not to every kritya-formed word.
As, मासदेयम् 'a debt repayable within a month.' So संवत्सरदेयं 'payable within a year.' त्र्यहदेयं 'repayable within three days.'
By using the word ऋण we indicate by implication any appointed time in general, and not merely a time for the payment of a debt. Therefore we get compounds in the following cases also:- पूर्वाह्नो गेयं साम 'the Sáma that should be sung in the morning.' प्रातरध्येयोऽनुवाकः 'the chapter that should be studied in the morning.'
Why do we say 'debt'? Observe मासे देया भिक्षा 'the alms that should be gives each month.',