Add misc item data constants

include/constants/items.h

@@ -490,6 +490,8 @@
 
 #define ITEM_TO_BERRY(itemId)(((itemId - FIRST_BERRY_INDEX) + 1))
 
+#define FIRST_MAIL_INDEX ITEM_ORANGE_MAIL
+
 #define NUM_TECHNICAL_MACHINES 50
 #define NUM_HIDDEN_MACHINES     8
 
@@ -506,6 +508,21 @@
 #define GOOD_ROD  1
 #define SUPER_ROD 2
 
+// Secondary IDs for bikes
+#define MACH_BIKE 0
+#define ACRO_BIKE 1
+
+// Item type IDs (used to determine the exit callback)
+#define ITEM_USE_MAIL        0
+#define ITEM_USE_PARTY_MENU  1
+#define ITEM_USE_FIELD       2
+#define ITEM_USE_PBLOCK_CASE 3
+#define ITEM_USE_BAG_MENU    4 // No exit callback, stays in bag menu
+
+// Item battle usage IDs (only checked to see if nonzero)
+#define ITEM_B_USE_MEDICINE 1
+#define ITEM_B_USE_OTHER    2
+
 // Check if the item is one that can be used on a Pokemon.
 #define ITEM_HAS_EFFECT(item) ((item) >= ITEM_POTION && (item) <= ITEM_0B2)