It discusses only open source software currently referred to as Bitcoin Core or software fully compatible with that reference version. Bloomberg says this is the only convertible virtual currency identified by the IRS in  Notice 2014-21.

Besides discussing basic descriptions of how Bitcoin works, the Portfolio consider consequences of trading and investing in Bitcoin, and the activities and selected transactions undertaken by investment entities, and foreign and tax-exempt investors. It also  identifies issues which pose novel or challenging tax aspects of Bitcoin.