I experienced this yesterday. I went to the airport a little early to complete my VAT refund and check my bags and noted the "SSSS" on my boarding pass when the agent printed it. I showed up to our gate (24, which is a bus gate) after most of the boarding had completed and let the agent checking my passport that I needed secondary screening and I was put into the area for that. A security agent appeared to have a list of all the SSSS passengers and checked my name off the list. Since I was forewarned of what was to happen from this thread, I had most of my carry-on items passed off to my wife before I got to the gate so I had a minimal amount of items to inspect. They just did a quick swab of my bag, electronics, waist, and shoes, and I was done. My wife was waiting for me on the bus and we rode out together to the tarmac to board our plane.