const time.stdArgShift

5 uses

	time (current package)
		format.go#L132: 	stdArgShift  = 16                 // extra argument in high bits, above low stdArgShift
		format.go#L133: 	stdMask      = 1<<stdArgShift - 1 // mask out argument
		format.go#L277: 					std |= (j - (i + 1)) << stdArgShift
		format.go#L672: 			b = formatNano(b, uint(t.Nanosecond()), std>>stdArgShift, std&stdMask == stdFracSecond9)
		format.go#L1064: 			ndigit := 1 + (std >> stdArgShift)