SU - vlasisku

1 on class
3 in definition
4 in notes

On grammatical class:

su: erase to start of discourse or text; drop subject or start over.

In definition:

si'oi: erases a SI, SA or SU cmavo; is to "redo" as SI/SA/SU is to "undo".
cmavrsu: x₁ is the selma'o "SU".
gugdesu'u: x₁ is the country with the code ISO-3166 SU (USSR) for people x₂.

In notes:

vicma'o: x₁ is an eraser word
de'ai: default value (re)specification/(re)assignment/(re)definition/over-write; set new default value (terbri-specific; permanent)
su'u'u'u'u'u'u'u: erasure word: delete everything that was ever said in Lojban.
nebmaugi: x₁ is a part of Lojban text representing rule 'null'