What does this "+" mean?

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TXFlyGuy

Well-Known Member
Joined
Apr 25, 2012
Messages
1,660
Location
Republic of Texas
On some P-51's near the data block, you will see a + sign.
I have been told it is simply a reference mark. And the latest explanation is that it represents "extended range". Like a B-777-200ER (Extended Range). I doubt it, but not sure.

What say you?

See it on this replica pictured:
P1030796.JPG
 
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