Fallout 4 Blue Circle on Right Side of Screen

This article is about the screen. For other uses, see Debug.

Screenshot showing the debug information

The debug screen is triggered when the F3 key is pressed. It shows the chunk cache, the memory usage, various parameters, the player's map coordinates and a graph that measures the game's current frame rate.

Legend [ ]

When the reducedDebugInfo gamerule is set to true, only the starred items are included, in order from top to bottom. The left side is more about the actual game and the right side is more about the player's system information.

Left side [ ]

Name	Description^[1] ^[2]
Version*	Displays the version, whether it is vanilla or not, or whether it is a snapshot or not.
fps*	The frame rate in frames per second.
T (first)*	Shows the max framerate ("inf" if Unlimited) and the Graphics type ("fast" if Fast, "fancy" if Fancy and "fabulous" if Fabulous!), including cloud settings ("fast-clouds" if Fast, "fancy-clouds" if Fancy and none if clouds are off), as well as if the player has VSync turned on or not.
B (first)*	The player's biome blend setting.
ms ticks*	The time it takes for a tick on the integrated server.
tx*	Number of packets sent by the client.
rx*	Number of packets received by the client.
C (first)*	Number of chunk sections rendered over the total number of chunk sections in the loaded area.
D*	Client-side render distance.
pC*	Pending chunks to be batched.
pU*	Pending uploads to video card.
aB*	Available buffers to use in the batching process.
E*	Number of rendered entities over total entities.
B (second)*	Unused, always 0. May previously have been the number of entities removed due to hidden chunks. ^{[ verify ]}
SD*	Simulation distance.
P*	Number of particles in world.
T (second)*	Displays the total number of entities (including mobs and dropped items) in loading chunk.
Client Chunk Cache*	The most chunks that can be loaded on the client.
ServerChunkCache	Its purpose is unknown.
Dimension FC	The current dimension of the player with the count of force loaded chunks (FC = Forceloaded Chunk).
XYZ	X: Player's location in blocks East of 0,0 (negative values are to the West). Y: Player's (feet) altitude in blocks (63 is overworld sea level, -54 is overworld lava flood level, 32 is nether lava sea). Z: Player's location in blocks South of 0,0 (negative values are to the North).
Block	The coordinates of the block the player's feet are in, in xyz format. Similar to XYZ as above, rounded down to a whole number. The numbers in square brackets display the location of the player within a chunk.
Chunk*	The location of the chunk within the world. In reduced mode, only the location within the chunk is displayed. The square brackets contain the chunk position in the region file, and the name of this region file that the player is currently in.
Facing	The direction in which a player is facing. Toward Positive X/Z indicates the player's alignment toward the x/z axis. The two numbers at the end indicate the player's horizontal (azimuthal) and vertical (altitudinal) rotation.
Client Light	The client-side light values, where a is the sky light level and b is the block light level. The first number is the total light level where the player's feet are. Note that there are a few caveats here due to the sky light level showing the light level the block would get from the sun in full daylight, but does not account for the lower light levels at night or during a storm. The second number is the amount of light from the sky at the block the player's feet are in. Same caveat as above. The third number is the amount of light from other blocks (e.g. torches) at the block the player's feet are in.
Server Light	The server-side light values. Exactly the same as the described in Client Light, but the first number "total light level" doesn't exist.
CH	Describes the Y coordinate of the highest block that exists at the player's current X/Z coordinates, client side. CH: client-side values S: The Y coordinate of the highest non-air block at this X/Z coordinate. M: The Y coordinate of the highest block at this X/Z coordinate that has a blocking-motion material or is liquid.
SH	Describes the Y coordinate of highest block that exists at the player's current X/Z coordinates, server side. SH: server-side values S: The Y coordinate of the highest non-air block at this X/Z coordinate. O: The Y coordinate of the highest block at this X/Z coordinate that has a blocking-motion material. M: The Y coordinate of the highest block at this X/Z coordinate that has a blocking-motion material or is liquid. ML: The Y coordinate of the highest block at this X/Z coordinate that has a blocking-motion material and is not leaves.
Biome	Shows the player what biome they are in.
Local Difficulty	Shows the difficulty of the chunk the player is in. See Difficulty on how this works. The second number in parentheses displays the number of in-game days the player has been in the world.
Multinoise	Shows the noise values used to generate terrain and biomes. Displayed only when using the `multi_noise` biome source. C: continentalness. Used to distinguish ocean and land. E: erosion. How flat the terrain is. Higher values result in flatter biomes, lower values in mountainous biomes. T: temperature. Used for biome placement, and does not affect terrain. H: humidity. Used for biome placement, and does not affect terrain. W: weirdness. Used for rivers and, in places with low erosion, to determine if the biome is in a valley, peak, or in between. Also used to determine the placement of unique biomes like sunflower plains and ice spikes.
Biome builder	Categorizes the noise values used to generate terrain and biomes. Displayed only when using the `multi_noise` biome source. PV: peaks and valleys. Can be one of Valley (rivers), Low, Mid, High, or Peak. C: continentalness. Can be one of Mushroom fields, Deep ocean, Ocean, Coast, Near inland, Mid inland, or Far inland. E, T, and H: erosion, temperature and humidity, respectively. Represent different ranges of noise values as numbers, where lower numbers are also lower actual values. Temperature and humidity can be 0 to 4, while erosion can be 0 to 6.
Terrain	Shows the noise values to generate certain aspects of the terrain.^{[ more information needed ]} PV: peaks and valleys. Derived from the weirdness noise value. O: height offset. A terrain spline that alters the base terrain elevation. F: squashing factor. A terrain spline/flattening factor that affects the "shatteredness" of terrain. Lower values lead to more noisy terrain like the shattered savanna biome. JA: jaggedness. A terrain spline determining the jaggedness of the terrain.
SC	Shows the total amount of mob-spawning chunks (usually 289).
M (first)	Shows the total amount of monsters that count toward the mob cap.
C (second)	Shows the total amount of creatures (passive mobs that spawn on a surface).
A (first)	Shows the total amount of ambient mobs (bats).
A (second)	Shows the total amount of axolotls.
U	Shows the total amount of underground water creatures (glow squids).
W (first)	Shows the total amount of water creatures (squids and dolphins).
W (second)	Shows the total amount of water ambient mobs (all 4 types of fish).
M (second)	Shows the total amount of misc entities.
Sounds	Represented by: Number of sounds playing/maximum of sounds playing. The first pair represents normal sounds like breaking or placing a block, moving or burning fire. The second pair represents streamed sounds, such as music, music from music discs, and loop ambience sounds. The mood value in parentheses indicates how close the player is to the next mood ambience sound being played (see Ambience#Mood algorithm).
Shader	The file path of the currently-active shader (within the "assets" directory of minecraft.jar). Displayed only if a shader is active.
Debug*	Tells the player whether the debug pie, or the FPS + TPS graphs are visible or not.
For help*	Tells the player to press F3 + Q for extra debug information; see below for more info.

Right side [ ]

Name	Description
Java*	The Java version the player is running and whether it is 32bit or 64bit.
Mem*	The amount of memory that the game uses (as a percent as well), over the max amount of memory the game can use.
Allocated*	The amount of memory the game has allocated from the max the game can use, also as a percent.
CPU*	The CPU, including how many cores it has, what brand, its exact model and at what speed the CPU runs (in GHz) that the player uses.
Display*	The resolution of Minecraft (as well as the name of the GPU company), the graphics card, the OpenGL version and what driver the player uses.
Targeted Block	Displays exactly what block the player is targeting, the block's coordinates & blockstates and what tags it has. Appears only when the player is looking at a block.
Targeted Fluid	Displays exactly what fluid the player is targeting, the fluid's coordinates & blockstates and what tags it has. Appears only when the player is looking at a block or fluid. If the player is targeting a non-fluid block, displays "minecraft:empty" instead.
Targeted Entity	Displays exactly what entity the player is targeting, nothing else. Appears only when the player is looking at an entity.

Profiler graph [ ]

Pie charts in the lower right of the ⇧ Shift +F3 debug screen display real-time profiling information. More detailed information about one section can be displayed by using the keys 1-9. Press 0 to go back to the previous section.

Screenshot of the debug pie chart in Java Edition 1.16.1.

Frame time graph [ ]

Bar chart in the lower left of the Alt +F3 debug screen displays real time measurement of milliseconds per frame with lines marking 16.7 and 33.3 milliseconds per frame, corresponding to 60 and 30 FPS respectively. The graph is color coded from green to yellow to red, with green being faster frame time, red being slower frame time, and yellow in between. In singleplayer and self-hosted LAN worlds (i.e. when running an integrated server), another graph, at the bottom right, shows milliseconds per tick (MSPT) with a line marking 50 MSPT, which is the maximum amount of time a game tick can take while maintaining 20 ticks per second (the intended rate). The color-coding is similar to the FPS graph.

More debug-keys [ ]

Text appears in chat for most debug keys listed here. Note that when using a specific key combination like F3 +N, F3 +B, etc., the debug screen does not open.

F3 +A : Reload all chunks.
F3 +B : Toggle visibility of hitboxes of visible entities. It also shows which direction entities are looking, as well as the entities eye level.
F3 +C : Copies the player's coordinates and rotation in the form of a /tp command.
- Holding for 10 seconds instead forces a debug crash. This generates error code -1, which is misinterpreted by launchers as "video driver error"
- Ctrl +F3 +C forces a Java crash instead of a regular Minecraft crash. However, with some keyboards, it triggers only with right control (or rarely, vice versa), thus using left control produces a regular crash.^[3]

Screenshot of the crash alert given in the chat while holding F3+C.

F3 +D : Clear chat history. Does not include recently typed messages and commands from ↑ and ↓.
F3 +G : Toggles visibility of the chunk borders around the player.
F3 +H : Toggles visibility of IDs of items, durability of tools, and armor hexcodes for color. It also shows the scale of maps and details of a firework rocket in a crossbow.
F3 +I : Copies server-sided block or entity data to the clipboard.
F3 +⇧ Shift +I : Copies client-sided block or entity data to the clipboard.
F3 +N : Cycle between Spectator mode and the previous gamemode. Switches to Creative mode if there is no previous gamemode. Requires cheats to be enabled.
F3 +P : Toggle automatic pause when Minecraft loses focus on / off.
F3 +Q : Gives help and shows all F3 + key combinations.
F3 +T : Reload textures, models, sounds, and any other resource pack contents.
F3 +F4 : Opens gamemode switcher menu. While holding down F3, a player can cycle between the game modes by pressing F4 and enter the selected gamemode after releasing F3
F3 +Esc : Toggle pause without pause menu (if pausing is possible). Singleplayer-only.
⇧ Shift +F3 : Opens the debug screen with the profiler graph.
Alt +F3 : Opens the debug screen with the Frame time graph.
(note that both graphs can be opened with ⇧ Shift +Alt +F3)
Alt +5 : Brings up command shortcut menu (Realms Only)
F3 +L : Generates Performance Metrics

When the reducedDebugInfo gamerule is set to true, the effects of F3 +B (entity hitboxes), F3 +G (chunk boundaries), F3 +C (copying coordinates), and F3 +I (copying block/entity data) are not shown. Holding down F3 +C to initiate a crash still works as expected, as well as Ctrl +F3 +C

History [ ]

The debug information from Indev, Infdev, and early Alpha.

Java Edition Classic
0.0.2a		The version number is now displayed in the top-left corner.
0.0.9a		Add the debug screen.
0.0.9a		The debug screen includes the fps, and chunk updates.^{[ verify ]}
Java Edition Indev
?		Added an option to turn on the debug screen. The current version name is always displayed even when the option is disabled.
Java Edition Alpha
v1.1.0		The debug screen is no longer listed as an option and now requires `F3` to be held down to activate.
v1.2.3		The coordinates have been added to the debug screen.
Java Edition Beta
1.3		The debug screen, along with other function key controls, has now become a toggle.
1.3		When the debug screen is open, it now shows numbers above every mob; these numbers being the mob's Entity ID. These numbers are visible through blocks, making `F3` a useful mob-finder.
1.7		The "f" coordinate has been made visible in the debug screen (facing direction).
1.8	Pre-release	The ability to see the level's seed has been added to the debug screen.
1.8	Pre-release	Entity numbers being shown above a mob's head have been removed from the debug screen. Some players felt that it was cheating and that it took away from the game.
Java Edition
1.0.0	October 2, 2011	The first images of a runtime performance profiler with a pie chart is revealed.
1.0.0	Beta 1.9 Prerelease 3	The profiler has been added to the debug screen.
1.2.1	1.2	Information about the biome and light level of the player's location have been added to the debug screen.
1.2.1	1.2	The seed in multiplayer has been made hidden from the debug screen and now shows as "0".
1.2.4		Pressing `F3` (`Fn` +`F3` on Mac and some laptops) brings up the debug screen, but without the graphs. The graph appears upon pressing `⇧ Shift` +`F3` (`Fn` +`⇧ Shift` +`F3` on Mac and some laptops).
1.3.1	12w18a	Information about the player's speed and whether the player is touching the ground have added to the debug screen.
	12w18a	Coordinates within the debug screen are now rounded to 5 digits.
	12w21a	Information about the world's seed has been removed from the debug screen, seen instead by pressing the chat key and typing `/seed`.
	12w21a	The frame time graph has been removed from the debug screen.
	12w30a	The y coordinate now shows both the feet level and the eye level.
1.4.2	12w39a	Fl, x and z chunk coordinates, and more rotation (f) information have been added to the debug screen.
	12w41a	`⇧ Shift` +`F3` now shows the profiler graph in the debug screen.
	12w41a	`F3` +`H` now shows durability on damaged tools, weapons and armor pieces.
1.4.4	1.4.3	`F3` +`B` now shows the hitbox around entities. At this point, the hitbox is white and opaque and does not have an outline.
1.7.2	1.7.1	`F3` +`B` visual changed. The entity hitbox is now completely transparent, with a thin white outline.
1.8	14w02a	The debug screen now shows which axis the player is facing after the cardinal direction: "Toward positive/negative X/Z".
	14w04a	The crosshair in the debug screen now displays 3 short colored lines to indicate the direction of each axis: x/red, y/green, z/blue.
	14w04a	The x coordinate line in the debug screen now appears bold when looking east/west, similarly the z coordinate line now appears bold when looking south/north.
	14w05a	Text within the debug screen now has a background.
		X, y, z, b, bl and other labels within the debug screen have been replaced with more understandable labels.
		"Light" is now the light levels at feet, not eyes.
	14w06a	X, Y, and Z title in the debug screen has been changed from 'Feet' in the previous snapshot, to 'XYZ'.
		A day counter, which increases by 1 every dawn, has been added to the debug screen.
		The debug screen now displays difficulty: Peaceful- 0.00, Easy- 0.75, Normal- 1.50, Hard 2.25 (but numbers slowly increase the longer the player is in an area).
		The debug screen now displays player rotation in degrees and quadrants.
	14w11a	On the right-hand side of the debug screen, a display now shows up if the player is looking at a block, showing its ID and block states.
	14w17a	All blocks now have their info displayed on the right-hand side of the debug screen.
	14w17a	The "Facing negative/positive x/z" from the debug screen has been removed.
	14w20a	The "Facing negative/positive x/z" has been readded to the debug screen.
	14w25b	`F3` +`B` now also shows which direction entities are looking using a blue line.
	14w25b	The line on the right-hand side that had displayed the name of the block model the player was looking at has been removed from the debug screen.
	14w29a	A 'Reduced Debug Info' toggle now exists within multiplayer settings to enable/disable reduced information on the debug screen.
	14w29a	The `reducedDebugInfo` gamerule allows the player to enable/disable reduced information on the debug screen. This overrides all 'reduced debug info' settings in clients.
	14w30a	The debug screen now displays how many chunk sections are being rendered currently and how many chunk sections are out of view in percent, the OpenGL version, display size, vendor and GPU.
	14w30a	"Vanilla" has been added to the version number within the debug screen.
1.8.2	pre1	The frame time graph within the debug screen has been readded and redesigned, so that it can now be activated using `Alt` +`F3`.
1.9	15w32a	`F3` +`N` now toggles between Creative and Spectator modes, when the player is in either of them. The player needs to be allowed to use `/gamemode` for this to work.
	15w43a	The debug screen now shows more information.
		`F3` +`Q` gives help and shows all `F3` + key combinations.
		`F3` +`F` now increases render distance by 1 (Minimum and Maximum are 2-32).
		`F3` +`⇧ Shift` +`F` now decreases render distance by 1 (Min and Max are 2-32).
		The debug screen now shows if the pie chart and fps chart are shown on screen.
		The debug screen now shows text in chat when the player reloads chunks, sounds, etc.
		The debug screen now does not open when the player uses a specific key combination like `F3` +`N`, `F3` +`B`, etc.
		`F3` +`S` has been removed from the debug screen, which previously reloaded sounds.
		`F3` +`T` now reloads all resource pack content, including sounds.
		Red, blue and green lines have now changed in size within the debug screen and now change relative to the GUI scale.
		The debug screen is now toggled when the `F3` key is released, instead of when it is pressed.
1.10	16w20a	`F3` +`G` toggles the visible chunk borders around the player.
1.10	16w20a	The 3 lines indicating direction now have a small black outline when looking at an area with bad contrast.
1.13	18w11a	Pressing `F3` +`C` now copies the player's current location to the clipboard in the form of a `/tp` command, though holding for 10 seconds and releasing still forces a debug crash.
	18w14a	The debug screen now gives a warning before forcing a debug crash.
	18w22c	The debug overlay now shows the fluid the player is looking at, separately from blocks.
	pre6	`F3` +`I` copies block or entity data to the clipboard.
	pre6	Added information about the time it takes for a tick on the integrated server, number of packets sent by the client (tx), and number of packets received by the client (rx).
	pre7	Added "Looking at liquid" row, which displays the targeted fluid's coordinates.
		"Looking at" row within the debug screen has been renamed to "Looking at block".
		"Targeted Block" information now targets through fluids. It displays information for blocks up to 16 blocks away.
		Added "Targeted Entity", which displays information for entities up to 16 blocks away.
		`F3` +`I` ^{[note 1]} has been changed to now be `⇧ Shift` +`F3` +`I`. It is now clarified that it copies the client-side data of targeted block or entity. It still can be used by anyone.
		Added `F3` +`I` to copy targeted block or entity server-side data to clipboard. It can be used only by operators.
1.13.1	18w30a	Added `Ctrl` +`F3` +`C` to force a JVM crash, instead of a regular crash.
1.13.1	18w31a	Added new fields for the current dimension and the related force loaded chunks.
1.14	18w43c	Pressing `Alt` +`F3` now shows TPS (ticks per second).
1.14	18w43c	Added `min`/`avg`/`max` tick times to help find stutters.
1.14.1	Pre-Release 1	Pressing `F3` +`Esc` now toggles pause without pause menu (if pausing is possible).
1.14.1	Pre-Release 1	Pressing `F3` +`N` when in Survival or Adventure mode now changes the player into Creative mode, if cheats are enabled.
1.15	19w38a	The chunk update counter has been removed from the debug screen.
1.15.2	Pre-Release 1	`F3` +`D` no longer clears recently typed messages and commands from `↑` and `↓`.
1.16	20w18a	The "Looking at block" and "Looking at fluid" were integrated into "Targeted block" and "Targeted fluid" located on the right side of the debug screen.
	20w18a	Added a new line detailing mob spawning in different categories.
	20w20a	Added gamemode switcher accessible with `F3` +`F4`.
	20w20a	`F3` +`N` now toggles between Spectator mode and the previous gamemode.
1.17	21w11a	Added `F3` +`L` to generate Performance Metrics.
1.18	Experimental Snapshot 1	Added two new lines: Multinoise and Terrain.
1.18.2	22w03a	Now contains the chunk position in the region file, and the name of this region file that player is currently in, in the end of the "Chunk" row.
1.18.2	22w03a	Moved the location of the player within a chunk from "Chunk" row, into the new square brackets at the end of the "Block" row.
1.19	22w12a	Removed the `F3` +`F` and `F3` +`⇧ Shift` +`F` hotkeys that change render distance.

Pre-1.8 legend [ ]

This section describes content that exists only in outdated versions of Minecraft.

This feature used to be in the game but has since been removed.

Name	Description^[4] ^[5]
C	Number of chunk sections rendered over total number of chunks. Counts all render passes: if a chunk section is rendered twice (because it contains both water and normal blocks, for example) then it is counted twice.
F	Number of chunk sections loaded outside the viewing distance. Counts all render passes.
O	Number of chunk sections removed through occlusion culling. Counts all render passes.
E (first row)	Number of empty chunk sections. These sections are skipped for one of two reasons: Either the chunk has not yet been loaded and rendered into polygons, or the section has nothing to draw in the current render pass. Counts all render passes.
E (second row)	Number of rendered entities over total entities
B	Unused, always 0.
I	Number of invisible entities
P	Number of particles on screen
T	Displays the player's max framerate
ALL	Displays the total number of loaded entities (including mobs and dropped items)
ServerChunkCache ChunkCache	The most chunks that can be loaded
x	Player's location in blocks East of 0,0 (negative values are to the West) and after the // is the player's chunk number with the block within the chunk in ()
y	Player's altitude in blocks (63 (62.9) is overworld sea level, 11 (10.9) is overworld lava flood level, 32 (31.9) is nether lava sea).
z	Player's location in blocks South of 0,0 (negative values are to the North) and after the // is the player's chunk number with the block within the chunk in ()
f	The direction in which a player is facing (south=0, west=1, north=2, east=3) and if the player walks toward x or z respectively
lc	Max section height for the chunk the player is in (uses cubic chunk sections, so heights display in multiples of 16 minus 1).
b	Shows the player what biome they are in.
bl	(for "block light") The amount of light from other blocks (e.g. torches) at the block the player's head is in. If the player stands on top of a torch, this field shows a light level of 13 instead of the expected 14, due to the player's head being one block away from it.
sl	(for sky light) The amount of light from the sky at the block the player's head is in. Note that the number shown here is accurate only during the day. It shows the light level the block would get from the sun in full daylight, but does not account for the lower light levels at night or during a storm.
rl	(for raw light) The total light level where the player's head is, equal to max (bl,sl). Note that because the "sl" field is factored in here, this field has the same caveats as that one.
ws	Walking speed.
fs	Flying speed.
g	On ground, Boolean value, true if the player touches the ground.
fl	The y-coordinate of the highest block where the player is able to stand, rounded up when standing on half-blocks, such as slabs. When above the void (where there is no block), it equals 0.
shader	The file path of the currently-active shader (within the "assets" directory of minecraft.jar). Displayed only if a shader is active.

Issues [ ]

Issues relating to "Debug screen" or "F3" are maintained on the bug tracker. Report issues there.

Trivia [ ]

Biome, and the lighting values do not display when the player is outside of the build limits.
Deeper into the profiler (⇧ Shift +F3), some tasks have numbers higher than 9 and can't be accessed. Pressing the two keys simultaneously does not open the task.

Gallery [ ]

Image from Notch showing an "unlicensed copy" message on the top corner of the screen.
A sneak peek of the performance profiler shown on Notch's Twitter on October 2, 2011^[6]
Showing the chunk borders debug feature
Showing the hitboxes debug feature

Notes [ ]

↑ F3 +I was used to copy targeted block or entity data to clipboard.

References [ ]

↑ http://gaming.stackexchange.com/questions/14990/minecraft-debug-screen
↑ http://www.minecraftforum.net/viewtopic.php?f=35&t=13231
↑ MC-135509; per comments there, some keyboards do not allow pressing those keys at the same time (as they are in the same vertical column, presumably). http://keyboardchecker.com/ can be used to check.
↑ http://gaming.stackexchange.com/questions/14990/minecraft-debug-screen
↑ http://www.minecraftforum.net/viewtopic.php?f=35&t=13231
↑ https://twitter.com/notch/status/120525867045765120

Minecraft: Java Edition

Versions

Demo
- Locations
PC Gamer Demo (Beta 1.3)

Development

Version history	Pre-Classic Classic Early Classic Creative Multiplayer Test Survival Test Late Classic Creative Indev Infdev Alpha Beta Full Release Development versions

Removed features
- Blocks
- Items
Unused features
Exclusive features
Mentioned features
- Sky dimension
Planned versions

Technical

Known bugs
- Minecraft Launcher
Hardware requirements
al_version
Block entity
Commands
- Functions
Crashes
Data values
- Classic
- Indev
- Pre-flattening
Data version
Debug screen
Formatting codes
Key codes
Minecraft Launcher
Protocol version
Resource location
Screenshot
Seed
Statistics
Tick
Spawn chunk
Coordinates

.minecraft	client.jar client.json launcher_profiles.json options.txt

Development resources	Anvil file format Chunk format Command storage format Entity format Generated structures format Level format Loot tables Map item format Model NBT format Obfuscation map Player format raids.dat format Raw JSON text format Region file format Structure block file format Schematic file format Scoreboard format Server list format sounds.json Subtitles villages.dat format
Legacy development resources	Classic level format Classic server protocol Indev level format Alpha level format server_level.dat

Multiplayer

Server
Minecraft Realms
Server list
server.properties
Server requirements

Game customization

Skins
Capes
Resource packs
Data packs

goodwingiathe.blogspot.com

Source: https://minecraft.fandom.com/wiki/Debug_screen