x1 is a part of Lojban text representing rule 'sumti-6' according to the first edition of the book 'The Complete Lojban Language'.
Inner structure of the rule: (LAhE # | NAhE BO #) (relative-clauses)? sumti /LUhU#/ | KOhA # | lerfu-string /BOI#/ | LA # (relative-clauses)? CMENE+ # | (LA | LE) # sumti-tail /KU#/ | LI # mex /LOhO#/ | ZO any-word # | LU text /LIhU#/ | LOhU any-word+ LEhU # | ZOI any-word anything any-word #. For the description of the syntax see jarnezi.