The db 0, 0 ; filler in every maps/*.asm script was written dw 00h in every SXY/*.SXY file. There's no comment about its original use.
From WORLDPOS.DMG:
Viridian Forest, between Route 2 and Pewter City:
; ef_equ_g WMAP_POS_TOKIWAMORI
; dw 503Ah,name_tokiwamori
name_tokiwamori:
db to__,ki__,wa__,no_,mo_,ri_
db EOM
Silph Co., between Saffron City and Route 11:
; ef_equ_g WMAP_POS_SILF
; dw 546Ch,name_silf
name_silf:
db si__,ru__,hu__,ka__,n__,pa__,ni__,bou@
db EOM
Safari Zone, between Fuchsia City and Route 19:
; ef_equ_g WMAP_POS_SAFARI
; dw 7C64h,name_safari
name_safari:
db sa__,hu__,aa__,ri__,zo__,bou@,n__
db EOM
Ice Path ("こおりのぬけみち" kōri no nuke-michi) was called Freezing ("氷結" hyouketsu):
name_hyouketu:
; db hi_,yyo_,u_,ke_,tu_
db ko_,o_,ri_,no_,nu_,ke_,mi_,ti_
db EOM
Note that Narusawa Ice Cave ("鳴沢氷穴" Narusawa Hyōketsu) is a volcanic cave located in the Aokigahara forest (aka the "Sea of Trees" or the "Suicide Forest") at the foot of Mt. Fuji (the basis for Mt. Silver).
Haunted House ("オバケやしき" obakeyashiki) was right after Ice Path:
name_obake:
db o__,ba__,ke__,ya_,si_,ki_
db EOM
Cinnabar Island ("グレン島" Guren-jima) was called Cinnabar Town ("グレンタウン" Guren Town):
name_guren:
; db gu__,re__,n__,ta__,u__,n__
db gu__,re__,n__,zi_,ma_
db EOM
Lavender Radio Tower ("シオンラジオとう" shion radio tō) was originally Pokémon Tower ("ポケモンタワー"):
name_tower:
; db poke@,ta__,wa__,bou@
db si__,o__,n__,ra__,zi__,o__,to_,u_
db EOM
Seafoam Islands ("双子島" futago-jima) were originally called Seafoam Islands Cave ("双子島洞窟" futago-jima dōkutsu):
name_futago:
; db hu_,ta_,go_,zi_,ma_,do_,u_,ku_,tu_
db hu_,ta_,go_,zi_,ma_
db EOM