On grammatical class:

bi'i
non-logical interval connective: unordered between ... and ...
bi'o
non-logical interval connective: ordered from ... to ...
mi'i
non-logical interval connective: ordered components: ... center, ... range surrounding center.

In definition:

ce'ei'oi
BIhI argument modifier: indicates dimensionality/length of tuple
cmavrbi'i
x1 is the selma'o "BIhI".

In notes:

bi'in zei uanta
x1 is a part of Lojban text representing rule 'interval' according to the first edition of the book 'The Complete Lojban Language'.