var golang.org/x/text/internal/language.altTagIndex

3 uses

	golang.org/x/text/internal/language (current package)
		lookup.go#L398: 	altTagIndex = [...]uint8{0, 17, 31, 45, 61, 74, 86, 102}
		lookup.go#L406: 			return Make(altTags[altTagIndex[-v-1]:altTagIndex[-v]]), true

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