Out of the ten poruthams prescribed by South Indian Astrological rules, it is called as "Vedha Porutham".
Hindu Rashi/ Nakshatra Matching
In South India, Vedha Matching (Porutham) of the bride and groom. It is mostly done when the marriages are arranged by the families of the boy and the girl.
Importance of Vedha Porutham
In thirumana porutham if this porutham is not properly made then the couple will face hardship in their life. In worst cases the couple will go for divorce. Certain nakshatras repel each other. Match made between such nakshatras will be disastrous.
Nakshatra - Vedha Nakshatra
Aswini - Kettai
Bharani - Anusham
Karthikai - Visakam
Rohini - Swathi
Thiruvathirai - Thiruvonam
Punarpoosam - Uthiradam
Poosam - Pooradam
Aayilyam - Moolam
Maham - Revathi
Pooram - Uthiratathi
Uthiram - Pooratathi
Hastham - Satayam
If boy and girls Nakshatra becomes vedha to each other it won't match.