Talk: Anvil file format

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ok, i updated my server to 1.2.3, and i want to revert to 1.1, becouse all the plugins are not working. (mostly /zmod) i need to convert it from anvill back to what ever it was befor. and the instruscions are not very clear on the page. can someone help me out? like a dumb i forgot to back it up. thank you in advance. my name is masterman467 im just to lazy to log in. –Preceding unsigned comment was added by 71.82.175.223 ^{(Talk|Contribs)} 03:24, 5 March 2012. Please sign your posts with ~~~~

Example Chunk

Below is an Example of an Anvil chunk. May be useful to others.

Sample Chunk NBT Structure

TAG_Compound(""): 1 entries
{
 TAG_Compound("Level"): 9 entries
 {
   TAG_List("Entities"): 0 entries
   {
   }
   TAG_ByteArray("Biomes"):      [256 values]
   TAG_Int64("LastUpdate"): 215588
   TAG_Int32("xPos"): -5
   TAG_Int32("zPos"): -112
   TAG_List("TileEntities"): 0 entries
   {
   }
   TAG_Int8("TerrainPopulated"): 1
   TAG_Int32Array("HeightMap"):      [256 values]
   TAG_List("Sections"): 5 entries
   {
     TAG_Compound("0"): 5 entries
     {
       TAG_ByteArray("Data"):          [2048 values]
       TAG_ByteArray("SkyLight"):          [2048 values]
       TAG_ByteArray("BlockLight"):          [2048 values]
       TAG_Int8("Y"): 0
       TAG_ByteArray("Blocks"):          [4096 values]
     }
     TAG_Compound("1"): 5 entries
     {
       TAG_ByteArray("Data"):          [2048 values]
       TAG_ByteArray("SkyLight"):          [2048 values]
       TAG_ByteArray("BlockLight"):          [2048 values]
       TAG_Int8("Y"): 1
       TAG_ByteArray("Blocks"):          [4096 values]
     }
     TAG_Compound("2"): 5 entries
     {
       TAG_ByteArray("Data"):          [2048 values]
       TAG_ByteArray("SkyLight"):          [2048 values]
       TAG_ByteArray("BlockLight"):          [2048 values]
       TAG_Int8("Y"): 2
       TAG_ByteArray("Blocks"):          [4096 values]
     }
     TAG_Compound("3"): 5 entries
     {
       TAG_ByteArray("Data"):          [2048 values]
       TAG_ByteArray("SkyLight"):          [2048 values]
       TAG_ByteArray("BlockLight"):          [2048 values]
       TAG_Int8("Y"): 3
       TAG_ByteArray("Blocks"):          [4096 values]
     }
     TAG_Compound("4"): 5 entries
     {
       TAG_ByteArray("Data"):          [2048 values]
       TAG_ByteArray("SkyLight"):          [2048 values]
       TAG_ByteArray("BlockLight"):          [2048 values]
       TAG_Int8("Y"): 4
       TAG_ByteArray("Blocks"):          [4096 values]
     }
   }
 }
}

--Stucuk 18:00, 11 March 2012 (UTC)

Thanks! Having an actual example is much more helpful than just the description. Posted right when I needed it, too. -- Orthotope 00:14, 12 March 2012 (UTC)

This seems relevant: Rumsey figured out what the biome ids actually correspond to: http://www.minecraftforum.net/topic/1034766-list-of-biome-ids/page__p__12881601#entry12881601 Orangy Tang 18:10, 21 March 2012 (UTC)

How many chunks are in a anvil mca file? The page for region mcr files mentioned this as being 16x16 for mcr regions. –Preceding unsigned comment was added by 74.92.206.53 ^{(Talk|Contribs)} 18:26, 6 May 2012. Please sign your posts with ~~~~

They're the same size as mcr files: 32x32 chunks, 512x512 blocks. -- Orthotope 00:07, 7 May 2012 (UTC)

Generation above old height limit

Today i was flying around in creative mode with the debug screen, and i noticed a tree where the top blocks were at Y = 132. i thought that it was not possible to have terrain generate above the old height limit of 127? if i can, i will have the seed soon. (version 12w22a) --204.14.13.53 16:40, 1 June 2012 (UTC)

Trees that used to get cut off will not now, that is an example of the difference. The new height limit allows blocks to generate at that height if it used to before but got cut off. LB 02:19, 8 July 2012 (UTC)

does that mean that blocks can go beyond the height limit and does that mean that you can use that to build up infenintley? --173.180.201.172 00:59, 15 June 2019 (UTC)

No, they're talking about blocks generating above the old height limit. Note that you are replying to a 7-year-old comment. – Nixinova

01:37, 15 June 2019 (UTC)

Moving/overwriting .mca files

If I want to copy an .mca file to another spot on my map, is it safe to overwrite existing .mca files with another .mca file? I tried this on a test world and it seems to have worked. I'm just not sure if there are any long term problems I might run into because of this.

No, it's not that simple. If there is an entity or TileEntity in the region then there's a big chance that the chunk it's in will be completely regenerated. 83.252.25.58 00:40, 24 August 2012 (UTC)

Biome data

What this page says about the biomes doesn’t match the data in my (1.15.2) world files, where I have a flat array of 1024 Ints instead of a 2d array of 16x16 Bytes. I think the right information is said in https://minecraft.gamepedia.com/Chunk_format, but I don’t really know and don’t want to copy the wrong information over. DHouck (talk) 08:15, 26 March 2020 (UTC)