Confusion over CPC 106: Abetment of Jus Termini and Abetment of Jus Tertii

Yaar samajh nahi aaya... I'm lost between CPC 106(2)(a) and (2)(b) here. It says, "abetment of jus termini" and "abetment of jus tertii" are different? Okay, so jus termini is the law of limitation, right? But then, it's also said that abetment of jus tertii is where someone abets the act of a third person in doing an act which would be right in itself but for some extraneous circumstance. But, isn't that abetment of jus termini?! Abetment of jus terimi deals with acts done after the prescribed period, and jus tertii talks about acts done by third parties... Warna kya hai, sirji? Pleeease help!