zai LAU cmavo

2-word letteral/shift: alternate alphabet selector follows.

On grammatical class:

ce'a
2-word letteral/shift: the word following indicates a new font (e.g. italics, manuscript).
lau
2-word letteral/shift: punctuation mark or special symbol follows.
tau
2-word letteral/shift: change case for next letteral only.
zai
2-word letteral/shift: alternate alphabet selector follows.

In definition:

cmavrlau
x1 is the selma'o "LAU".

In notes:

burfava
x1 is a part of Lojban text representing rule 'lerfu-word' according to the first edition of the book 'The Complete Lojban Language'.
epsi bu
digit/number: dual ε of dual number in linear algebra; square root of 0