Add documentation on download filesystem layout

website/src/docs/faq/downloads.md

@@ -42,3 +42,33 @@ No, you must choose a single location. Internal storage performs better than ext
 However, in some cases, this might not function as intended.
 
 A quick solution is to create the `.nomedia` file yourself, name it as such, and place it in your downloads folder. If the issue pertains to local source, put the `.nomedia` file in the respective local folder.
+
+## How are downloads organized on the filesystem?
+They are stored as `downloads/Source Name/Manga Name/Chapter Name (abcdef).cbz`.
+The `abcdef` string is the first 6 hexadecimal digits of the MD5 hash of the URL of the chapter, so that if two chapters have the same name, they won't try to write to the same filename.
+In the case of a scanlator, it is `Scanlator Name_Chapter Name` instead of just `Chapter Name`.
+
+Because of the prevalence of operating systems like Windows which have arbitrary limitations on special characters in filenames, by default Mihon will avoid using certain characters in filenames, specifically: `"*:<>?\|`.
+Of course, `/` is also banned.
+All of these characters are replaced by underscores if they appear in source, manga, chapter, or scanlator names.
+
+Some users have reported using exceptionally buggy operating systems which also have problems with other Unicode characters, such as (but not necessarily limited to) emojis.
+If you must use Mihon with such an operating system, you can enable the option in the advanced settings for "Disallow non-English filenames", which will prevent any non-English (non-ASCII) characters from being used in filenames.
+Such characters will be replaced with their hexadecimal representations instead.
+The special characters mentioned above are still replaced with underscores, if present, rather than hexadecimal.
+
+None of the above considerations affect the way series and chapters are displayed in Mihon, which is based on their metadata rather than filenames.
+Because the local source reads comic metadata files, if present, its functioning is also not affected by filename changes if you convert an external source download directory into a local source directory.
+
+If you need to change the "Disallow non-English filenames" option, you may need to do some manual work to ensure that Mihon can still find your existing downloads.
+Chapter filenames do not need to be changed, as Mihon is able to check multiple options for a chapter filename, and will find the already-downloaded chapters.
+Manga and source directory names, however, need to be updated manually if they contain non-ASCII characters.
+Here is an example:
+
+```text
+./例 ソース (ALL)/最高のマンガ！/Scanlator Name_始まり_182cce.cbz
+./e4be8b20e382bde383bce382b9 (ALL)/e69c80e9ab98e381aee3839ee383b3e382acefbc81/Scanlator Name_e5a78be381bee3828a_182cce.cbz
+```
+
+The inability for a device to handle Unicode characters in filenames is a bug.
+Please consider contacting your device or operating system vendor to report this, or consider using a standards-compliant device in future, if possible.

website/src/docs/guides/local-source/index.md

@@ -82,6 +82,9 @@ You can refer to the following example:
 Mihon will see three chapters in a single series.
 The path to the folder with images must contain both the series title and the chapter name (as seen above).
 
+Note that this is the same folder structure used by downloads of non-local sources.
+However, the filename format is not required to be the same; for example, Mihon adds a disambiguating hash based on the chapter URL when downloading chapters, but you do not need to do this.
+
 ### Archive files
 
 Archive files such as `ZIP`/`CBZ` are supported but the folder structure inside is not.