The lerfu shifts (BY1) consist of these cmavo: ga'e, ge'o, je'o, jo'o, lo'a, na'a, ru'o, se'e, to'a.
For past usage, I am searching through the corpus I have collected of 900 kilobytes of pure-Lojban text. The corpus includes all texts published at lojban.org/files/texts, many large texts from the Wiki, IRC logs, and texts from the CVS server such as Alice.
ga'e is only used correctly in algebra, to mark variables named with capital letters. It occurs one lerfu from the end of a lerfu string, so that it seems to have the same effect as tau.
to'a is never used correctly.
lapoi pelxu ku'o trajynobli contains the sentence ".itu'e ga'e ca cpedu fi do to'a". ga'e and to'a here both act as pro-sumti, which was probably not intended. Here, ga'e and to'a were probably intended to "capitalize" (emphasize) the words between them, but as lerfu modifiers they cannot modify the emphasis of words.
None of these are used anywhere in the corpus, except that the utterance "zo ru'o" appeared on IRC in response to someone typing a line of Russian text.
zai has not been assigned to this section, but it has a similar function to the above cmavo. It is also not used anywhere in the corpus.
This word is not used in the corpus.
This word is not used in the corpus.
The scope of a letteral shift needs to be defined. I will elaborate on Arnt's specification in BPFK Section: lerfu Forming cmavo:
A letteral shift lasts until another shift of the same type replaces it, it is cancelled by na'a, or the end of the lerfu string is reached.
(The sole usage of ga'e assumed that it would end at the end of a lerfu string, which seems reasonable.)
It is not specified where a se'e construct should end; I propose that it should be able to be terminated with na'a, because na'a terminates other sorts of shifts.
Since my job is to specify the meanings of these constructions, I will begin working on the mappings from Lojban letters to other alphabets.
Greek:
abu = alpha
by = beta
dy = delta
ebu = epsilon
fy = phi
gy = gamma
y'y = eta
ibu = iota
ky = kappa
kybu= chi
ly = lambda
my = mu
ny = nu
obu = omicron
py = pi
ry = rho
sy = sigma
sybu= psi
ty = tau
tybu= theta
ubu = upsilon
xy = xi
ybu = omega
zy = zeta
(I'm keeping this around in case anyone still wants to consider it.)
The alphabet shifts have not seen any usage, and in fact to use them requires there to exist a mapping from Lojban lerfu to the letters in that alphabet that is known to the listener.
There is already a mechanism for naming arbitrary characters: bu. The Greek letter alpha can be referred to much more clearly with alfas bu than with ge'o abu (na'a). There do not exist mappings to other alphabets, nor is there a demand for such mappings.
Given that Lojban does not seem to be intended for holding multilingual spelling bees, and that a dictionary containing many unused cmavo with bizarre functions could confuse learners of the language, I propose that alphabet shifts (including zai as well) should not appear in the dictionary.
Deprecating these six unused cmavo will not invalidate any past usage.
ga'e has been used legitimately, and it has a clear purpose, so it should remain and its behavior should be specified. to'a is then necessary for completeness. There are also definite situations in which it would be useful to use na'a, although it has not actually been used in the corpus.
se'e is a different sort of cmavo, and it has a conceivable purpose, so it should remain in the dictionary. Specifically, if Lojban is used in the future to communicate with computers, a computer would not necessarily understand either alfas bu or ge'o abu, but if an "alpha" character needed to be conveyed to it, it could be told the Unicode character code for "alpha" instead. Of course, I expect se'e never to be used by one human talking to another.