lu li'u cmavo-compound

empty (grammatical) string/text/utterance

Not: empty word, empty symbol. See also: zoi'ai'e.

On affix form:

x1 travels/journeys/goes/moves via route x2 using means/vehicle x3; x1 is a traveller.

In definition:

x1 is a quantity of/contains/is made of lutetium [Lu]
x1 (lu; quote) is said/expressed by x2, followed by expression x3 (lu; quote), via expressive medium x4, and then continuing on/proceeding/serially resuming to express/say x5 (lu; quote), and then x6 (lu; quote), and then x7 (lu; quote), ... (open-ended terbri structure of arbitrarily many sumti slots).
lu bu
pro-sumti: refers to the last complete {lu}-quotation

In notes:

x1 (quoted text) is a “bu letteral” of character x2 (zoi quote).
x1=v1=k1 is a word/quotation crossing other words/quotations, meaning/defined by x2=v2, located at x3=k3
x1 is the empty utterance/text
x1 (quote) is a zi'evla/fu'ivla categorizer particle/morpheme/unit with meaning/indicating category x2, having properties x3, and that is appended in zi'evla (full word) x4, in language x5
explicit "mu'o'u"-orientation marker
universal famyma'o: terminates the most recently opened construct or clause.
do'u'o (exp!)
question word: which utterance?
otherwise lojbanic name, ending in a vowel; multiple names delimited by pauses.
Named reference. It converts a sumti into another sumti. The converted sumti points to the referent the name of which is the referent of the unconverted sumti.
unevaluated mekso as name.
convert a grammatical quotation to a tanru unit; x1 expresses/says the quoted text for audience x2 via expressive medium x3.
Marks an endpoint of a quote/string/expression and specifies that (relative to the original) the quote/string/expression so marked is complete, accurate, and well-portrayed by the quote/string/expression on the relevant side of the excerpt, including wrt all relevant information and when factoring in the content and context of the quotation-external discourse in which said quote/string/expression appears.
connective modifer/limiter
abstraction described by quoted text
zai'u (exp!)
Quote conversion: the sentence(s)/bridi (possibly plural) is/are syntactically correct and semantically intended by the utterer if the outermost layer of quotes (markers) which immediately follows were to be omitted/removed, but the quoted text is in fact a quote (of the indicated type) from some source.
quotes a selbri.
zoi'ai'e (exp!)
empty string/text/word
x1 (quoted text) is a fragment/incomplete statement/question/utterance/proposition/text with intended meaning x2 in the context/under conditions x3 (default: the currently relevant context)
x1 is an object described as x2, x3, ... (termset representing serializable tree structure compatible with JSON format of attribute-value pairs).
x1 is Aries [astronomical constellation/astrological sign].
xa zei sumtika
x1 is a part of Lojban text representing rule 'sumti-6' according to the first edition of the book 'The Complete Lojban Language'.