const time.stdSeparatorShift

3 uses

	time (current package)
		format.go#L174: 	stdSeparatorShift = 28                 // extra argument in high 4 bits for fractional second separators
		format.go#L496: 	return code | ((n & 0xfff) << stdArgShift) | 1<<stdSeparatorShift
		format.go#L504: 	if (std >> stdSeparatorShift) == 0 {