Weird integral symbol : $\mathrel{\int\!\!\!\!\!-}$

Question

What does this integral sign mean ($\int$ with line going through the middle)?

$$ \mathrel{\int\!\!\!\!\!\!-} $$

(It had something to do with the Beckenbach-Radó Theorem)

Answer 1

One common usage of this symbol is average: The integral divided by the measure of the domain of integration.

Answer 2

Also used for the Cauchy Principal Value of an integral.