A word on FIRST
FIRST is the Forum of Incident Response and Security Teams. Since 1990, when FIRST was founded, its members have resolved an almost continuous stream of security-related attacks and incidents including handling thousands of security vulnerabilities affecting nearly all of the millions of computer systems and networks throughout the world connected by the ever growing Internet.
FIRST brings together a wide variety of security and incident response teams including especially product security teams from the government, commercial, and academic sectors.

TLP means Traffic Light Protocol, it is a protocol created by the Special Interest Group of FIRST (FIRST TLP SIG).