x1 is a ridiculous (useless, etc) cmavo of selma'o x2 by standard x3
The cmavo doesn't have to be experimental. I'm still mad they wasted monosyllabic cmavo space on a bunch of letteral stuff. Ex.: zo «tei» je zo «foi» cu roflma'o fi mi. Etymology: English ROFL + -ma'o- (rafsi of cmavo).