Well from 4.16 to 4.17 I wanted to change the center items. The old code placed every item - requiring you to count out squares, very painful and it would have driven me nuts. So I used a feature I learned existed in the game which enables me to define a blueprint string, and place the items in a loop. But this caused an issue. The X,Y location of capture is remembered in a blueprint, but you can choose absolute placement 0,0. But this means the new 0,0 is the corner of the BP, that would suck always calculating the offset of every new blueprint. So the fix - put a Roboport, which is the center item in my base, in the new blueprint. Enumerate the blueprint - find the Roboport - use that as an offset, remove the roboport from the BP and add my special Roboport that attracts biters, then lay those items in the new base. So the bug ? Well I needed to exclude the yellow chests from the BP, and lay them manually, because I needed a handle to the storage chests and fill them with stuff. I put the yellow chests in the new BP and then I placed them again on top of the blueprint chests, and factorio doesn't like that. Fixed in next version.

What I plan to do with this new easy ability to modify center? Heck I can store many different layouts for center, and allow the game host to choose the items they want in center. I may have choices like - more energy, less energy, or say NO CENTER items, and automatically lay the first power with one coal drill and belts already hooked up. The clears the base, but the Roboport has to go somewhere, so I'd lay that potentially between the oil items, also covering the power setup. Note that in the latest setup I give you free walls around center - which you can move and put on the bridge before biters start their attacks.