Hi DImster
thanks for feedback and ideas to talk about.
I love this topic Tempodi 
My pleasure to get the interest of QB64 coders.
The implied should be the value can be equal to min but not a value less than min. A value less than min should not be intheRange. If our range is  10 to 20 and the value is 9, that 9 would be less than the min of 10. ??? so what am I missing in this Logical Operator???
At the starting time, also I was thinking about
 IMP as the word 
imply but this is wrong and it brings us in the wrong direction. We use in human language this word with the meaning IF...THEN... while IMP seems to be a mathematical  imply that formally has as name
 Material Implication or
 Material Conditional.
read here if you want to get more deep informations  
https://en.wikipedia.org/wiki/Material_conditionalSo it seems that we must think about IMP as we think about + of the sum with its feature. It is an operator that gives False only if the first condition is True and the second condition is False. This is the path to set the right conditions in the two branches of IMP and to get back the desired result.
Well the function has the goal to return True (-1/ NOT 0) if the third parameter is between the first and the second parameters.
let's test the expression   
-  intheRange = 0  '<---- this is the default result (False/ No) 
-     intheRange  = (- value  <=-  max ) IMP (- value  <=-  min )   '<-- this is the expression that using IMP answer to the question " Is value between min and max?
-     intheRange  = NOT-  intheRange ' <-- really the above expression calculates the OutOfRange so we must NOT the result
Min  Max  Value    (value <= max) IMP (value <= min)            (NOT    (value<=max))  OR  (value <=min)
 10   20      9        (9<=20)   IMP  (9<=10)                              (NOT     (9<=20))        OR    (9<= 10)
                               True   IMP    True   -------> True                (NOT   True)       OR  (True)  ------> True
 10  20     21         21 <= 20  IMP  21<= 10                               NOT (21<=20)   OR (21<= 10)
                                  False  IMP   False  ---> True                     NOT False OR False ------> True
 10  20     11         11<= 20  IMP 11<=10                                NOT(11<=20)  OR (11<=10)
                                  True  IMP    False ---> False                     NOT True OR  False  -----> False
changing the > with < and viceversa we get the one shot InTheRange
Min  Max  Value    (value >= max) IMP (value >= min)            (NOT    (value>=max))  OR  (value >=min)
 10   20      9        (9>=20)   IMP  (9>=10)                              (NOT     (9>=20))        OR    (9>= 10)
                               False   IMP    False   -------> True                (NOT   False)       OR  (False)  ------> True
 10  20     21         21 >= 20  IMP  21>= 10                               NOT (21>=20)   OR (21>= 10)
                                  True  IMP   True  ---> True                     NOT True OR True ------> True
 10  20     11         11>= 20  IMP 11>=10                                NOT(11>=20)  OR (11>=10)
                                False    IMP   True ---> True                     NOT False OR  True  -----> True
So the code of the FUNCTION InTheRange will be
-  intheRange = 0  '<---- this is the default result (False/ No) 
-     intheRange  = (- value  >=-  max ) IMP (- value  >=-  min )   '<-- this is the expression that using IMP answer to the question " Is value between min and max?
And with this last sentence I feel to have finished to share my new knowledge about IMP.
PS Thank you, I have got a new InTheRange in oneshot!
Now I'll try to give an universal wellworking also with negative numbers. Next time.