This command marks a specified map with a map flag given. Map flags alter the
behavior of the map, you can see the list of the available ones in
'db/const.txt' under 'mf_'.

The map flags alter the behavior of the map regarding teleporting (mf_nomemo,
mf_noteleport, mf_nowarp, mf_nogo) storing location when disconnected
(mf_nosave), dead branch usage (mf_nobranch), penalties upon death
(mf_nopenalty, mf_nozenypenalty), PVP behavior (mf_pvp, mf_pvp_noparty,
mf_pvp_noguild, mf_nopvp), WoE behavior (mf_gvg,mf_gvg_noparty), ability to use
skills or open up trade deals (mf_notrade, mf_novending, mf_noskill, mf_noicewall),
current weather effects (mf_snow, mf_fog, mf_sakura, mf_leaves, mf_rain, mf_clouds,
mf_fireworks) and whether day/night will be in effect on this map (mf_indoors).