# What does the 'B' parameter represent in Wikipedia's page on window functions?

I was trying to learn some more window functions and was referencing the Wikipedia article on the subject. I've noticed on a lot of the plots, there appears to be a capitalized and italicized letter B. What is this parameter? I can't find any reference to it on the page. link to wikipedia article And here's a photo that features two plots, each having an associated 'B' parameter with them. imgur What is this?

Mathematically, the noise equivalent bandwidth of transfer function H is the bandwidth of an ideal rectangular filter with the same peak gain as H that would pass the same power with white noise input. In the units of frequency f (e.g. hertz), it is given by: $$B_{noise}={\frac {1}{|H(f)|_{max}^{2}}}\int _{0}^{\infty }|H(f)|^{2}df.$$