This read-write value selects which 802.1X authentication method, chap(1), pap(2), or eap(3), the switch uses when relaying supplicant credentials to the authentication server. Admins set it to match what the RADIUS server and client supplicants actually support, since a mismatch causes all authentication attempts on the device to fail. For example, an admin would set this to eap(3) to support wireless-style EAP authentication instead of the CHAP default.