Do nether strongholds only spawn within a certain radius?

In Minecraft beta, normal strongholds only spawned within a certain distance of 0,0, so they would never appear in a world which was explored beyond that radius.

In Minecraft 1.0, do nether strongholds have a limit like this, or will they appear at any distance? Can you keep exploring and find unlimited nether strongholds?


Nether Fortresses are closer to regular dungeons than they are to strongholds - that is to say, there's no set limit, and they spawn all over the place.

Here's a picture from AMIDST, a stronghold-finder tool with the Nether Fortress overlay active.

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And here's a picture of another random portion of the same seed.

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There's a definite pattern (though I don't know the exact code) to their position, and it extends in all directions with the map.