Ka-vi-fe was a concept within Vulcan society which meant "challenge" and was used between two members of the race during melee combat. Savaj and Spock entered into the ka-vi-fe by the Designers who sought to understand the nature of the aggression during the 23rd century. (TOS novel: The Prometheus Design) This form of ritual challenge may be distinct from the kal-if-fee, or it could be simply an alternate spelling.