I was reading a combat report from a Mosquito mission in 1943. In the rport, the report mentions that "Mosquito closed in and no resins were seen neither was target showing IFF". I was fortunate to speak with the Naviator (age 91) who told me IFF means Identification Friend or Foe, but does not recall what 'no resins' means. He said IFF is the terminolgy that was used in identifying friendly or enemy aircraft. If your radar was on, and a plane showed up, he said it was Friendly. If nothing showed up, he said it was a possible enemy or your radar was not on! Either way he said, proceed with caution towards the aircraft. Does anyone have any idea about 'no resins'?
I spent some time surfing the next and came up with the result of some type of low or dim formation lights referred to as 'resins' by the crew. I found this link which gets a bit out of control discussing the topic. http://www.britmodeller.com/forums/index.php?showtopic=27665