This read-only object reports which ITU-T annex (regional DSL variant, e.g. Annex A/B/M) the line negotiated with the far end during handshake. Knowing the negotiated annex matters because it determines the frequency plan and spectral compatibility rules in effect, which affects both achievable speed and interference with other services on the same cable. For example, an admin diagnosing an unexpectedly slow VDSL line might check this object to confirm the handshake settled on the annex expected for that region's wiring plan rather than a mismatched one.