When someone joins a channel/room, they join it as a regular user. After that, they might be opped, half-opped, and/or voiced. That would return the results checking to see if then person with nickname is a regular user in the specified channel. When a person is opped, half-opped or voiced, then they are no longer a regular user in that channel.
In an if/else statement, the first item can be referenced using $v1 and the second item using $v2.