This may be a helpful link:
http://www.apnss.org/39Flags.htmAnd yes, Trainwreck is correct there is no microprinting on the Scott #3979 coil (perf. 9.75 vert.) printed by SSP.
Likewise, there is no microprinting on the Scott #3980 coil (perf 11 vert.) printed by AVR.
But just to confuse things,
THERE IS MICROPRINTING on the Scott #3981 coil (perf 9.5 vert.) printed by APU. The microprinting on that issue is "USPS" located on top red flag stripe.