What is "kaiyoppu"

Kaiyoppu (Malayalam: കയ്യൊപ്പ്; English: Signature) is a 2007 Malayalam film written by noted writer Ambikasuthan Mangad. The film was produced and directed by Ranjith and stars Mammootty, Kushboo, and Mukesh. This film is considered as one of the best from Ranjith and was critically acclaimed.