PR #47500, #47501, #47557, #47588.

code/__DEFINES/components.dm

@@ -77,6 +77,10 @@
 #define COMSIG_ATOM_ATTACK_HAND "atom_attack_hand"				//from base of atom/attack_hand(): (mob/user)
 #define COMSIG_ATOM_ATTACK_PAW "atom_attack_paw"				//from base of atom/attack_paw(): (mob/user)
 	#define COMPONENT_NO_ATTACK_HAND 1							//works on all 3.
+//This signal return value bitflags can be found in __DEFINES/misc.dm
+#define COMSIG_ATOM_INTERCEPT_Z_FALL "movable_intercept_z_impact"	//called for each movable in a turf contents on /turf/zImpact(): (atom/movable/A, levels)
+
+
 /////////////////
 
 #define COMSIG_ENTER_AREA "enter_area" 						//from base of area/Entered(): (/area)

code/__DEFINES/misc.dm

@@ -511,5 +511,10 @@ GLOBAL_LIST_INIT(pda_reskins, list(PDA_SKIN_CLASSIC = 'icons/obj/pda.dmi', PDA_S
 #define VOMIT_TOXIC 1
 #define VOMIT_PURPLE 2
 
+// possible bitflag return values of intercept_zImpact(atom/movable/AM, levels = 1) calls
+#define FALL_INTERCEPTED		(1<<0) //Stops the movable from falling further and crashing on the ground
+#define FALL_NO_MESSAGE			(1<<1) //Used to suppress the "[A] falls through [old_turf]" messages where it'd make little sense at all, like going downstairs.
+#define FALL_STOP_INTERCEPTING	(1<<2) //Used in situations where halting the whole "intercept" loop would be better, like supermatter dusting (and thus deleting) the atom.
+
 //Misc text define. Does 4 spaces. Used as a makeshift tabulator.
 #define FOURSPACES "&nbsp;&nbsp;&nbsp;&nbsp;"