1. 1 on class
2. 1 in definition
3. 1 in notes

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'.