It inverts the adjoining brivlas while preserving their original tanru relation. So "melbi nixli" (seltau-tertau) and "nixli co melbi" (tertau-seltau) are the same in meaning.

Such inversion comes in handy when you want to insert some sumti into the seltau on the level of the main bridi:

ko'a nixli co melbi mi
She is a girl who looks beautiful to me

Otherwise:

ko'a melbi be mi nixli
She is a beutiful-to-me type of girl

>>525

Can I say "[melbi co mi tricu]"? What about "[melbi tricu co xamgu]"?

>>529

"mi", which is a sumti, cannot come after "co", which joins only words that can be a selbri.

"melbi tricu co xamgu" is grammatical. It's read as

((melbi tricu) co (xamgu))

, and is identical in meaning with

(xamgu ke (melbi tricu))

or

(xamgu (melbi bo tricu))

Inversion of tanru: http://jbotcan.org/cllc/c5/s8.html