The "+" is not modifying the name in any way. It is stricly a mathematical operator, meaning to add the result from the function. Along those lines, the "ancient ones" used to start a formula using "+" instead of "=", so you would type "+SUM(A:A)" (sans quotes) to make a formula. XL is smarter now, and converts this to a formula, but occassionally you still see something like:

=+SUM(A:A)

In this case, the "+" at the beginning serves no purpose, other than to let you know that the person who wrote the formula has been writing formulas for a long time.