Info: set

Usage: 'set <variable> <value>' or 'unset <variable>'

The list of open-ended environment variables is: allow_gtrain, armoury_even_a, armoury_even_b, armoury_odd_a, armoury_odd_b, berserk_percent, brief, channel_color, channel_output, color_room, cols, confuse, firstaid, format_numbers, fprompt, full_armoury, herb_ver, homepage, ii_opts, keep_sent, login_cmd, logout_cmd, more_lines, msp, no_aid, no_build, party_list, private_info, prompt, quiet_repair, shut_poison_up, shut_save_up, skills_display, tell_from_colour, tell_to_colour, timezone, tprompt, trader_options, whitelist, and who_opts

The list of closed-ended environment variables and their accepted values is:
ansi                          : off or on
chime_hour                    : no or yes
color_room                    : no or yes
defense                       : guild or mud
listen_to_pose                : no or yes
lottery                       : no or yes
no_channels_wrap              : no or yes
no_combat_prompt              : on
party_security                : accepted, blocked or off