On grammatical class:

jo'i
join mathematical expression (mex) operands into an array.

In definition:

cmavrjo'i
x1 is the selma'o "JOhI".

In notes:

ci zei mektika
x1 is a part of Lojban text representing rule 'operand-3' according to the first edition of the book 'The Complete Lojban Language'.