References: golang.org/x/text/internal/language.

const golang.org/x/text/internal/language._XC

one use

	golang.org/x/text/internal/language (current package)
		tables.go#L1043: 	_XC  = 326

The pages are generated with Golds v0.7.6. (GOOS=linux GOARCH=amd64)