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+## Paths
+
+The game makes use of several kinds of directories that are often referred to in this wiki.  
+Note that in any context where you have to specify a path, you can use the `$X` shorthands specified below for these.  
+For example, if you want to refer to a directory called `dir` that sits right next to `pd.exe`, you can write `--basedir $E/dir` instead of `--basedir C:/Games/PD/dir`.
+
+### Environment paths
+
+#### Working directory (`.`)
+Directory where you ran the game from.  
+If you didn't run it from the command line, normally it will be the same as the executable directory.
+
+#### Executable directory (`$E`)
+Directory where the game executable (i.e. `pd.exe` or `pd`) is.
+
+#### Home directory (`$H`)
+Writable directory that's used for configs and saves in case the working directory and the executable directory are not writable.  
+On Windows: `%APPDATA%/perfectdark`  
+On Linux: `~/.local/share/perfectdark`
+
+### Game paths
+
+#### Base directory (`$B`)
+Directory where your ROM file is.  
+If this is not overridden with `--basedir` or `--portable`, the game will try to find a directory called `data` in the following locations in that order:
+1. Working directory
+2. Home directory.
+3. Executable directory.
+
+#### Save directory (`$S`)
+Directory where the game stores your config and EEPROM save file.  
+If this is not overridden with `--savedir` or `--portable`, defaults depend on the OS.  
+**On Windows**: working directory if it's writable, home directory otherwise.  
+**On Linux**: working directory if a config file is already present in it, home directory otherwise.
+
+#### Mod directory (`$M`)
+Directory that contains modded files.  
+Will override anything in the base directory and in the ROM on a file-by-file basis, i.e. the game will try to load a file from the mod directory first, but if it isn't present it will load it from the base directory or the ROM.  
+Not set by default. Set with `--moddir`.