COMPARE Full Length

Why must I COMPARE one less than the length of a string for it to recognize
a match? I create two strings in the target image, $Revision being the
shorter one to match, $Revision2 being the longer one to scan. At compile
time the longer one is scanned with a DO loop starting from the first
character address. If the shorter is found at the I'th position it is
DUMPC'ed.

TARGET
S" $Revision:x" DUP 1+ ALLOT 2CONSTANT $Revision
S" x$Revision:x1" DUP 1+ ALLOT 2CONSTANT $Revision2
INTERPRETER
: $Revision, $Revision2 OVER + SWAP ?DO $Revision { 1- } I OVER COMPARE DUP
0= IF I 13 DUMPC DROP ELSE CR . THEN LOOP ;
$Revision,

Without 1- :
-1
1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1

With 1- :
-1
120CB 24 52 65 76 69 73 69 6F 6E 3A 78 31 FF $Revision:x1.
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
-1
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Received on Tue Sep 17 2002 - 06:05:06 PDT