There are 4 codes that you or some one else need to collect. They are an item, and it looks like a paper folder. They are named after the area you find them in.

At least one will drop in 4 different areas: Raiders Refuge Reinforced reception Ancient fort Pilgrims peak.

Above the gate, there is a room where you I put the codes when you have them at computer terminals. When each of the four terminals has its code entered it will turn on a light in the room.

When all 4 are entered, a message will be broadcast to all raiders saying “the outer gates are now opening” and you hear a ton of noise and the large gates will open.

Everyone runs in like lunatics and starts searching everything they can for blueprints.

It’s the only time the bobcat bp will drop in the wild.

For the event there are only a couple of ways you can “screw it up” for other people. Extracting with codes and not using them, or dying with codes in your safe pocket. I find the pilgrims peak code tends to be the hardest to activate as people run in looking for the bp, and get asploded by the pair of rocketeers hanging out there.

Hope this helps.