# What does a superscript plus sign mean in integral notation?

In the following paper, there is some notation which I don't understand:

• It is the positive part (hence the exponential is $1$ for negative arguments). Had the entire integrand be canceled, another function would have been used as a factor to the integrand, possibly denoted as $(x\ge0)$. – Yves Daoust Feb 15 '17 at 22:22