On grammatical class:

nu'a
convert mathematical expression (mex) operator to a selbri/tanru component.

In definition:

cmavrnu'a
x1 is the selma'o "NUhA".

In notes:

re zei taulka
x1 is a part of Lojban text representing rule 'tanru-unit-2' according to the first edition of the book 'The Complete Lojban Language'.