I don’t see a version number, but the 2018-02-22 is the original release number. Maybe yours is a first edition? (I don’t know if they’ve done any updated physical releases.)
Here’s what mine (digital) looks like:
If I may be a bit forward, please read through my recent post on the passive voice in Japanese:
Passive voice used to give me trouble, but since learning that Japanese doesn’t have a passive voice, and learning what’s actually happening, it’s made it a lot easier for me to grasp. It still took encountering it a few times and thinking it through as a “receptive form” to get it down, but that was so much faster and easier than dealing with trying to understand it as an English passive voice grammar construct.