Replace explicit z-level checks with defines

code/controllers/subsystem/communications.dm

@@ -30,7 +30,7 @@ SUBSYSTEM_DEF(communications)
 
 /datum/controller/subsystem/communications/proc/send_message(datum/comm_message/sending,print = TRUE,unique = FALSE)
 	for(var/obj/machinery/computer/communications/C in GLOB.machines)
-		if(!(C.stat & (BROKEN|NOPOWER)) && (C.z in GLOB.station_z_levels))
+		if(!(C.stat & (BROKEN|NOPOWER)) && is_station_level(C.z))
 			if(unique)
 				C.add_message(sending)
 			else //We copy the message for each console, answers and deletions won't be shared

code/controllers/subsystem/mapping.dm

@@ -146,7 +146,7 @@ GLOBAL_LIST_EMPTY(the_station_areas)
 	var/list/station_areas_blacklist = typecacheof(list(/area/space, /area/mine, /area/ruin))
 	for(var/area/A in world)
 		var/turf/picked = safepick(get_area_turfs(A.type))
-		if(picked && (picked.z in GLOB.station_z_levels))
+		if(picked && is_station_level(picked.z))
 			if(!(A.type in GLOB.the_station_areas) && !is_type_in_typecache(A, station_areas_blacklist))
 				GLOB.the_station_areas.Add(A.type)
 

code/controllers/subsystem/minimap.dm

@@ -61,7 +61,7 @@ SUBSYSTEM_DEF(minimap)
 	for(var/z in z_levels)
 		send_asset(client, "minimap_[z].png")
 
-/datum/controller/subsystem/minimap/proc/generate(z = 1, x1 = 1, y1 = 1, x2 = world.maxx, y2 = world.maxy)
+/datum/controller/subsystem/minimap/proc/generate(z, x1 = 1, y1 = 1, x2 = world.maxx, y2 = world.maxy)
 	// Load the background.
 	var/icon/minimap = new /icon('icons/minimap.dmi')
 	// Scale it up to our target size.

code/controllers/subsystem/shuttle.dm

@@ -325,7 +325,7 @@ SUBSYSTEM_DEF(shuttle)
 				continue
 
 		var/turf/T = get_turf(thing)
-		if(T && (T.z in GLOB.station_z_levels))
+		if(T && is_station_level(T.z))
 			callShuttle = 0
 			break