Lojban is a young language, but a language which prides itself on being fully and explicitly documented... almost always. In a couple of instances, topics alluded to in these lessons are still somewhat up in the air. Though what the lessons themselves say about Lojban grammar you can rely on, there are some side issues on which the dust has not yet settled as of this writing. This appendix covers two issues in particular; you do not need to go through this on your first reading of the lessons, but once you start reading, writing, and speaking Lojban, this appendix tries to explain some things you may bump into, and which might strike you as odd.
In Lesson 8, we said that vo'a refers back to 'the first sumti of this bridi'. This is all well and good when your sentence only contains one bridi. But when it doesn't — and it often doesn't — we have a problem. In
does vo'a refer to la kris. ("Chris knows that Pat loves her"), or la pat. ("Chris knows that Pat loves herself")? In
la kris. djuno ledu'u la pat. prami vo'a
does vo'a swap la djun. with la pat. ("Chris knows that Pat loves June and vice versa, that they love each other"), or with la kris. ("Chris knows that Pat loves June, and June knows that Chris loves Pat")?
la kris. djuno ledu'u la pat. prami la djun. soi vo'a
The answer will, perhaps, shock you. In both cases, vo'a is acting as what is called in linguistics a reflexive: it refers back to something in the same sentence. In natural languages, reflexives almost always refer back to subjects; and in Lojban, the x1 place is as close as you will get to a subject. The difference is, when you have this kind of embedding, the reflexive can refer back to the subject of the verb it is immediately tied to (short-distance reflexive), or it can refer all the way back to the subject of the entire sentence (long-distance reflexive.)
Now, herself in English is a short-distance reflexive: if Chris knows that Pat loves herself, then Chris knows that Pat loves Pat, not Chris. Reflexives in almost all languages are short-distance; relatively few languages allow their reflexives to be long-distance as well as short-distance (Chinese), or have long-distance reflexives distinct from short-distance (Icelandic). So if vo'a corresponds to herself, then it too is short-distance.
And here, we have some unfortunate confusion. The Complete Lojban Language describes vo'a as short-distance. But the earlier material defining the language had it as long-distance; and that is in fact how just about all Lojbanists use it.
Why would Lojbanists do something seemingly so perverse, and contrary to how most languages work? Basically, because their attitude towards pro-sumti is quite different to normal language attitudes towards pronouns. Lojbanists would like to have unambiguous pro-sumti — pro-sumti whose reference can be determined with certainty. Now, to do a short-distance reflexive's job (refer to something in the same bridi), you can very often use ri instead of vo'a. But to do a long-distance reflexive's job (refer to something in the main bridi of the sentence), ri usually will not work, because you will have mentioned other sumti in between. This leaves you stuck with ra, which is deliberately as vague as natural language pronouns. "But," reasons the average Lojbanist, "if I wanted natural language vagueness, I'd be speaking a natural language. And because I will need to refer back to sumti of the main sentence often (main and embedded bridi tend to involve the same cast of characters), I'd rather vo'a serve as an unambiguous way of doing just that."
So whether because it was what they got used to in 1991 (and they didn't want to relearn the language in 1997), or because they thought vo'a would be more useful that way, Lojbanists interpret la kris. djuno ledu'u la pat. prami vo'a as saying that Chris knows that Pat loves her, not herself. So Lojbanists use vo'a as a long-distance reflexive.
... almost always. There are two occasions when you will occasionally see short-distance interpretations instead. The first is when the long-distance interpretation doesn't make sense for some reason. For example, the x1 place of the main bridi contains the embedded bridi containing vo'a — so a long-distance reading would get terribly recursive: lenu la suzyn. jmina fi le vo'a ctebi cinta cu cinri makes sense as "Susan putting on her lipstick is interesting", but not as the horridly recursive "Susan putting on x's lipstick is interesting" — where x is "Susan putting on x's lipstick", where x is "Susan putting on x's lipstick", where x is "Susan putting on x's lipstick"...)
The second occasion is (you guessed it) soivo'a. People are used to thinking of soivo'a as vice versa, which forces a short-distance interpretation. And while there are reasons you would want vo'a in general to be a long-distance reflexive, there isn't much occasion for a long-distance reciprocal.
If usage to date were the only thing that determined the meaning of Lojban words (as is usually believed by the community), we might say that vo'a is by default long-distance, but becomes short-distance under special circumstances (such as soivo'a.) But past usage is not the only factor in determining what Lojban words mean. Lojbanists cherish their precious few unambiguous pro-sumti, and most would rather not lose one. So, while some Lojbanists have said (and will likely continue to say) things like la kris. djuno ledu'u la pat. prami la djun. soi vo'a, meaning that Pat and June love each other, most Lojbanists think they are being wrong, and would prefer something like la kris. djuno ledu'u la pat. prami la djun. soi ri.
Note: The phrase la djun. soi ri counts as one sumti, so thankfully ri here does not refer to June!
Incidentally, there are truly unambiguous alternatives to vo'a, if you're not comfortable with the way this is heading. We won't explain them here, but you might be able to guess how they work anyway. The guaranteed short-distance reflexive in Lojban is lenei, and the guaranteed long-distance reflexive is leno'axiro. (leno'a is enough when there is only one level of bridi nesting.) In the unlikely case your use of vo'a is met with blank, uncomprehending stares, you can try using these instead.