What types of investments can be included in interval funds?

Interval fund is a fund structure that can be used to gain exposure to a wide variety of asset types. Multi Strategy Growth and Income Fund(MSFDX) summarizes it quite well on its website:

“Interval funds may include a wide range of investments and investment strategies, including listed, non-listed, public, and private investments. Some investments include equity real estate, commercial real estate loans, small- and middle-market loans, institutional funds, and private funds. The point is that through interval funds, individual investors who may not be able to directly access the underlying investments can invest in a portfolio of products typically reserved for institutions, endowments, and high-net-worth investors.”