Well, that was not it, but this one is cool too. This is what I'm talking about:
This little icon that looks like a clock. It outputs all variables being used and in what states they are used. Here is an example with one of my characters:
;---------------------- Integer variable list ----------------------
; var(0):= 765, 766, 19000, 19002, 8150, 8151, 8600
; var(1):= 19000, 19002
; var(2):= 1015, 1025, 3005, 3055, 3205, 3255, 19000, 19002
; var(3):= 40
; var(4):= -3
; var(5):= -3, 1005
; var(6):= -3
; var(7):= -3
; var(8):= -3
; var(9):= -2, 1005, 1015, 1025, 1075, 3005, 3055, 3205, 3255, 3705, 3706
;var(10):= 750, 800, 1000, 1010, 1020, 1030, 1070, 1080, 1100, 1110, 1200, 1210, 1250, 1260, 1300, 1350, 1400, 1500, 1600, 1005, 1025, 1075, -1
;var(13):= -2, 810, 820, 1321, 1326, 3501, 1006, 1015, 1025, 1026, -1
;var(15):= -2, 810, 820, 1010, 1030, 1080, 1110, 1210, 1260, 1321, 1326, 1350, 3000, 3050, 3100, 3150, 3200, 3250, 3500, 3600, 3700, 1006, 1015, 1025, 1026, 1076, 3005, 3055, 3705, 3706, -1
;var(16):= -2, 810, 820, 1321, 1326
;var(17):= 900, 905, -2, 3000, 3050, 3100, 3150, 3200, 3250, 3500, 3600, 3700
;var(18):= -3, 1006, 1015, 1025, 1026, 1076, 3005, 3055, 3205, 3255
;var(19):= 800, 805, 810, 820
;var(20):= 900, 905, -2, 1010, 1030, 1080, 1110, 1210, 1260, 1350, 3000, 3050, 3100, 3150, 3200, 3250, 3500, 3600, 3700
;var(21):= -3, 3000, 3050, 3100, 3150, 3200, 3250, 3500, 3600, 3700
;var(22):= -3, 3000, 3050, 3100, 3150, 3200, 3250, 3500, 3600, 3700
;var(23):= -3, 8610
;var(24):= 770
;var(25):= -3, 1010, 1030, 1080, 1101, 1110, 1210, 1260, 1350
;var(26):= 760, 761, -3
;var(30):= -2
;var(31):= 200, 201, 210, 211, 212, 213, 220, 221, 222, 230, 240, 241, 250, 251, 400, 410, 420, 430, 440, 450, 600, 610, 620, 630, 631, 640, 641, 642, 650, 651, 800, 1100, 1110, 1200, 1210, 1250, 1260, 1305, 1310, 1315, 1317, 1605, 2910, 3100, 3150, 3500, 3600
;var(32):= 200, 201, 210, 211, 212, 213, 220, 221, 222, 230, 240, 241, 250, 251, 400, 410, 420, 430, 440, 450, 600, 610, 620, 630, 631, 640, 641, 642, 650, 651, 800, 1100, 1110, 1200, 1210, 1250, 1260, 1305, 1310, 1315, 1317, 1605, 2900, 2910, 3100, 3150, 3500, 3600
;var(33):= 200, 201, 210, 211, 212, 213, 220, 221, 222, 230, 240, 241, 250, 251, 400, 410, 420, 430, 440, 450, 600, 610, 620, 630, 631, 640, 641, 642, 650, 651, 800, 1100, 1110, 1200, 1210, 1250, 1260, 1305, 1310, 1315, 1317, 1605, 2900, 2910, 3100, 3150, 3500, 3600
;var(34):= 200, 201, 210, 211, 212, 213, 220, 221, 222, 230, 240, 241, 250, 251, 400, 410, 420, 430, 440, 450, 600, 610, 620, 630, 631, 640, 641, 642, 650, 651, 800, 1100, 1110, 1200, 1210, 1250, 1260, 1305, 1310, 1315, 1317, 1605, 2900, 2910, 3100, 3150, 3500, 3600
;var(35):= 200, 201, 210, 211, 212, 213, 220, 221, 222, 230, 240, 241, 250, 251, 400, 410, 420, 430, 440, 450, 600, 610, 620, 630, 631, 640, 641, 642, 650, 651, 800, 1100, 1110, 1200, 1210, 1250, 1260, 1305, 1310, 1315, 1317, 1605, 2900, 2910, 3100, 3150, 3500, 3600
;var(36):= 200, 201, 210, 211, 212, 213, 220, 221, 222, 230, 240, 241, 250, 251, 400, 410, 420, 430, 440, 450, 600, 610, 620, 630, 631, 640, 641, 642, 650, 651, 800, 1100, 1110, 1200, 1210, 1250, 1260, 1305, 1310, 1315, 1317, 1605, 2900, 2910, 3100, 3150, 3500, 3600
;var(38):= -2
;var(39):= -3
;var(40):= 5900
;var(41):= -2
;var(43):= 1025, 3705, 3706
;var(45):= 5901
;var(53):= 770, -2, 1010, 1030, 1080, 1110, 1210, 1260, 1350
;var(54):= 7650
;var(55):= 7650
;var(56):= 7650
;var(58):= -3
;---------------------- Float variable list ----------------------
; fvar(5):= 900, 905, -3, 3000, 3050, 3100, 3150, 3200, 3250, 3500, 3600, 3700
; fvar(8):= -2
;fvar(10):= -2
;fvar(11):= -2, 1005, 1015, 1025, 1075, 3005, 3055, 3205, 3255, 3705, 3706
You can see it skips var(11), which means it is not being used anywhere and it is safe to use it. Vars 46 ~ 52 too, and so on.
Just keep in mind it also tracks helpers variables. In my example, var(0) states are all helpers, the character is not using it. To make sure (if you don't know the states), you need to manually check those.