You may call someone's attention to the fact that you are addressing them by using doi followed by their name. The sentence

means “Oh, John, I'm talking to you” . It also has the effect of setting the value of do ; do now refers to “John” until it is changed in some way in the conversation. Note that Example 2.55 is not a bridi, but it is a legitimate Lojban sentence nevertheless; it is known as a “vocative phrase” .

Other cmavo can be used instead of doi in a vocative phrase, with a different significance. For example, the cmavo coi means “hello” and co'o means “good-bye” . Either word may stand alone, they may follow one another, or either may be followed by a Lojbanized name surrounded by pauses.

Commands are expressed in Lojban by a simple variation of the main bridi structure. If you say

you are simply making a statement of fact. In order to issue a command in Lojban, substitute the word ko for do . The bridi

instructs the listener to do whatever is necessary to make Example 2.58 true; it means “Talk!” Other examples:

The ko need not be in the x1 place, but rather can occur anywhere a sumti is allowed, leading to possible Lojban commands that are very unlike English commands:

The cmavo ko can fill any appropriate sumti place, and can be used as often as is appropriate for the selbri:

and

both mean “You take care of you” and “Be taken care of by you” , or to put it colloquially, “Take care of yourself” .