fix WITHIN to match ANS FORTH (low ≤ test < high)

startup.4th

@@ -664,6 +664,9 @@ DEFER THROW-UNWIND ( k*x n -- i*x <noreturn> )
 \ Return -1, 0, or 1 if n is respectively negative, zero, or positive
 : SIGNUM ( n -- -1 | 0 | 1 ) DUP 0<= SWAP 0>= - ;
 
+\ True if n1 >= n2 && n1 <= n3, false otherwise
+: WITHIN  ( n1|u1 n2|u2 n3|u3 -- flag )  OVER - -ROT - U> ;
+
 \ Double-cell versions of standard numeric words
 : DABS ( d -- +d ) 2DUP D0< IF DNEGATE THEN ;
 : DMIN ( d1 d2 -- d1|d2 ) 2OVER 2OVER D> IF 2SWAP THEN 2DROP ;
@@ -990,22 +993,18 @@ CREATE LEAVE-ORIG NULL ,
       - ?DUP IF -ROT 2>R NIP 2R> LEAVE THEN
    LOOP ▪ 2DROP SIGNUM ;
 
-\ True if n1 >= n2 && n1 <= n3, false otherwise
-: WITHIN ( n1|u1 n2|u2 n3|u3 -- flag )
-   OVER - -ROT - U>= ;
-
 \ Convert a character to lowercase or uppercase, respectively
 : TO-LOWER ( ch1 -- ch2 )
-   DUP [CHAR] A [CHAR] Z WITHIN IF [[ CHAR a CHAR A - ]] + THEN ;
+   DUP [CHAR] A [[ CHAR Z 1+ ]] WITHIN IF [[ CHAR a CHAR A - ]] + THEN ;
 : TO-UPPER ( ch1 -- ch2 )
-   DUP [CHAR] a [CHAR] z WITHIN IF [[ CHAR a CHAR A - ]] - THEN ;
+   DUP [CHAR] a [[ CHAR z 1+ ]] WITHIN IF [[ CHAR a CHAR A - ]] - THEN ;
 
 \ If ch is a digit (any base) return the value in range [0, 36) and TRUE
 \ Otherwise just return FALSE
 : >DIGIT ( ch -- u TRUE | FALSE )
-   DUP [CHAR] 0 [CHAR] 9 WITHIN IF [CHAR] 0 - TRUE EXIT THEN
-   DUP [CHAR] A [CHAR] Z WITHIN IF [[ CHAR A 10 - ]] - TRUE EXIT THEN
-   DUP [CHAR] a [CHAR] z WITHIN IF [[ CHAR a 10 - ]] - TRUE EXIT THEN
+   DUP [CHAR] 0 [[ CHAR 9 1+ ]] WITHIN IF [CHAR] 0 - TRUE EXIT THEN
+   DUP [CHAR] A [[ CHAR Z 1+ ]] WITHIN IF [[ CHAR A 10 - ]] - TRUE EXIT THEN
+   DUP [CHAR] a [[ CHAR z 1+ ]] WITHIN IF [[ CHAR a 10 - ]] - TRUE EXIT THEN
    DROP FALSE ;
 
 \ Convert a string in the given base to an unsigned double-cell number