Chapter 2: A Quick Tour of Lojban Grammar, With Diagrams
You may call someone's attention to the fact that you are addressing them by using “doi” followed by their name. The sentence
✥14.1 doi djan.
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 ✥14.1 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 pause and a name. (Vocative phrases with “doi” do not need a pause before the name.)
Commands are expressed in Lojban by a simple variation of the main bridi structure. If you say
✥14.4 do tavla -- ===== You are-talking.
you are simply making a statement of fact. In order to issue a command in Lojban, substitute the word “ko” for “do”. The bridi
✥14.5 ko tavla -- =====
instructs the listener to do whatever is necessary to make ✥14.4 true; it means “Talk!” Other examples:
✥14.6 ko sutra -- ===== Be fast!
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:
✥14.7 mi tavla ko -- ===== -- Be talked to by me Let me talk to you.
The cmavo “ko” can fill any appropriate sumti place, and can be used as often as is appropriate for the selbri:
✥14.8 ko kurji ko -- ===== --
✥14.9 ko ko kurji -- -- =====
both mean “You take care of you” and “Be taken care of by you”, or to put it colloquially, “Take care of yourself”.