BIP 112 — CHECKSEQUENCEVERIFY

BIP 112 (CHECKSEQUENCEVERIFY) is a consensus soft fork adding an opcode that lets a script require a minimum relative age (per BIP 68 semantics) before an output can be spent. It activated in mid-2016 alongside BIPs 68 and 113. Repository status: Deployed.

Debate relevance: Core to Lightning's security model — penalty and HTLC timeout paths depend on relative timelocks — so it surfaces in most 'how does Lightning stay honest' exchanges. Common misstatements: CSV vs CLTV confusion (relative vs absolute timelocks), and attributing Lightning's dispute windows to BIP 65 alone.