more content polish

4 files changed, 70 insertions, 64 deletions

diff --git a/documents/album.md b/documents/album.md
index ca170b2..7b79f7c 100644
--- a/documents/album.md
+++ b/documents/album.md
@@ -34,22 +34,27 @@ Referenced as `album:directory`; extra links: `[[album-commentary:directory]]`,
 ### Essential info fields
 
 * `Album`: album name
+  * [Learn about naming albums and tracks for HSMusic.](../guidelines/albums-and-tracks.md#name-albums-and-tracks-according-to-bandcamp-release)
 * `Directory`: unique identifier among other albums
+  * [Learn about the Directory field, used by almost every wiki object.](../guidelines/common-fields.md#directory-field)
   * This is used for the URL the album will be accessed at: https://hsmusic.wiki/album/DIRECTORY/
   * Groups and other wiki objects reference an album by its directory: `album:DIRECTORY`.
-  * This is usually generated automatically from the album's name. [Learn more.](../guidelines/common-fields.md#directory-field)
-  * Just for albums, the directory should match the filename, e.g. *Homestuck Vol. 5* automatically gets the directory `homestuck-vol-5` and its data is saved in the file `album/homestuck-vol-5.yaml`. (The filename isn't actually processed for any data purposes, it's just easier to navigate if it matches the directory.)
+  * An album's filename should match its directory - for example, *Homestuck Vol. 5* automatically gets the directory `homestuck-vol-5` and its data is kept in the file `album/homestuck-vol-5.yaml`. (The filename isn't actually processed for any data purposes; it's just easier to locate an album's data this way.)
+* `Color`: theme color representing album
 * `Date`: album release date
 * `Cover Art Date`: date cover art created/added, if different from album release date
+* `Default Track Cover Art Date`: date track art created/added, if different from album release date
+  * On HSMusic, this is used for "anthology" art projects where the fan community creates art for each track in an album that originally released without any art. Check out [Homestuck Vol. 5](https://hsmusic.wiki/album/homestuck-vol-5/) and [Beyond Canon](https://hsmusic.wiki/album/beyond-canon/) for examples!
+  * If one or a few tracks vary from most of the album, give the track its own `Cover Art Date` field.
 * `Date Added`: date album added to wiki
-* `Color`: theme color representing album
-* `URLs`: web URLs for album playback or purchase
 
 ### Content fields
 
+* `URLs`: web URLs for album playback or purchase
 * `Commentary`: album-wide commentary from anyone involved in making it
-  * [Learn more about formatting the Commentary field.](../guidelines/common-fields.md#commentary-field)
+  * [Learn how to format the Commentary field.](../guidelines/common-fields.md#commentary-field)
 * `Additional Files`: bonus files associated with the album, e.g. album booklet, desktop wallpapers, credits files
+  * [Learn how to format the Additional Files field.](../guidelines/common-fields.md#additional-files-field)
 
 ### Configuration & layout
 
@@ -58,22 +63,25 @@ Referenced as `album:directory`; extra links: `[[album-commentary:directory]]`,
 * `Has Track Numbers`: display track numbers in main track listing and sidebar (default: true)
 * `Listed on Homepage`: include this album in automatically generated listings on the main homepage (default: true)
 * `Listed in Galleries`: include this album in automatically generated group gallery pages (default: true)
-* `Default Track Cover Art Date`: date track art created/added, if different from album release date; provides default which may be overridden by a track's `Cover Art Date` field
-* `Cover Art File Extension`: corresponds to media file (`cover.jpg`, `cover.png`)
-* `Track Art File Extension`: corresponds to media files; provides default which may be overridden by a track's `Cover Art File Extension` field
 
 ### Relational fields
 
 * `Artists`: compositional artists who were largely responsible for the entire album, usually used for solo albums
+* `Cover Artists`: visual artists who created the album's cover artwork
 * `Wallpaper Artists`: visual artists who created the album's wallpaper art; setting this enables displaying custom wallpaper art for the album
-	* `Wallpaper Style`: CSS property/values to apply to the wallpaper for light tweaks of the original asset
-	* `Wallpaper File Extension`: corresponds to media file (`bg.jpg`, `bg.png`)
 * `Banner Artists`: visual artists who created the album's banner art; setting this enables displaying a banner for the album
-	* `Banner Style`: CSS property/values to apply to the banner for light tweaks of the original asset
-	* `Banner File Extension`: corresponds to media file (`banner.jpg`, `banner.png`)
-	* `Banner Dimensions`: precise dimensions of banner image file e.g. `1100x158` (used to avoid layout shift when loading album page)
-* `Cover Artists`: visual artists who created the album's cover artwork
-* `Default Track Cover Artists`: visual artists who were largely responsible for the entire album's track artworks; may be overridden by a track's `Cover Artists` field
+* `Default Track Cover Artists`: visual artists who were largely responsible for the entire album's track artworks
+  * If one or a few tracks vary from most of the album, give those tracks each its own `Cover Artists` field.
+  * If most of the tracks in an album have the same cover artists but one or a few tracks don't have unique cover art at all, give those tracks each the field `Has Cover Art: false`.
+* `Wallpaper Style`: CSS property/values to apply to the wallpaper for light tweaks of the original asset
+* `Banner Style`: CSS property/values to apply to the banner for light tweaks of the original asset
+* `Banner Dimensions`: precise dimensions of banner image file e.g. `1100x158` (used to avoid layout shift when loading album page)
+* `Wallpaper File Extension`: corresponds to media file (`bg.jpg`, `bg.png`)
+* `Banner File Extension`: corresponds to media file (`banner.jpg`, `banner.png`)
+* `Cover Art File Extension`: corresponds to media file (`cover.jpg`, `cover.png`)
+* `Track Art File Extension`: corresponds to media files (`sburban-jungle.png`)
+  * If one or a few tracks vary from most of the album, give those tracks each its own `Cover Art File Extension` field.
+  * [Learn about file extension fields.](../common-fields.md#file-extension-fields)
 * `Groups`: links album to group documents, which generally represent bands, online communities, specific projects, etc
 * `Art Tags`: art tags representing characters or features present in the album's cover artwork
 
diff --git a/documents/track.md b/documents/track.md
index bff8078..5ba85ff 100644
--- a/documents/track.md
+++ b/documents/track.md
@@ -14,80 +14,62 @@ Track documents are stored in album files; after the album header document, use
 
 Referenced as `track:directory`.
 
-* `Track`: track name
-  * See [Album & Track Guidelines](../guidelines/albums-and-tracks.md#name-field).
+### Essential info fields
 
+* `Track`: track name
+  * [Learn about naming albums and tracks for HSMusic.](../guidelines/albums-and-tracks.md#name-albums-and-tracks-according-to-bandcamp-release)
 * `Directory`: unique identifier among other tracks
+  * [Learn about the Directory field, used by almost every wiki object.](../guidelines/common-fields.md#directory-field)
   * This is used for the URL the track will be accessed at: https://hsmusic.wiki/track/DIRECTORY/
   * Tracks and other wiki objects reference a track by its directory: `'track:DIRECTORY'`.
-  * If this isn't provided, it will automatically be generated from the title similarly to how Bandcamp works. It's tuned for English titles, so most other languages are best off specifying the directory manually.
-  * Guideline: Use all lowercase, avoid non-ASCII characters, and reflect how a human reads the title: "Riches to Ruins Movements I & II", `riches-to-ruins-movements-i-and-ii`. Exercise some leeway for troll typing quirks: "We Are +og3th3r", `we-are-tog3th3r`.
-  * Guideline: Directories are always unique for each of a given type of document. If two tracks would have the same directory, distinguish by album or else artist: `disc-1-lofam4`, `i-dont-want-to-miss-a-thing-aerosmith`.
-  * Note: We don't currently have set guidelines for Japanese and other non-Latin scripts. (Compare: 暗闇の中の光, `light-in-the-darkness`, and がんばってＤＡＶＩＤさん, `vaporwave-2016-track11`.)
-
 * `Duration`: track listening duration
-  * **Examples:**
+  * These are written in standard "hour:minute:second" format, e.g:
     * `0:57` (57 seconds)
     * `4:13` (4 minutes, 13 seconds)
     * `3:05:20` (3 hours, 5 minutes, 20 seconds)
-  * If this isn't provided, track listings will display as `(_:__)`, and the track will be treated as zero seconds long (no duration).
-  * Guideline: If a track doesn't have a clear-cut duration (e.g, dynamic loops ripped from old console games), it's probably best to leave it as unset.
-
+  * If `Duration` isn't provided, track listings will display `(_:__)`, and the track will be skipped when summing together lengths to get an album's total duration.
+  * On HSMusic, if a track doesn't have a clear-cut duration (e.g, dynamic loops ripped from video games which didn't get an official in-game soundtrack release), don't include a duration for the track at all.
 * `Date First Released`: date of original release for tracks that were made available prior to album release (and other special cases)
-  * Guideline: This is pretty much exclusively for organization purpose on artist pages, where it doesn't make sense to chronologically position a track at one time when it was first released years earlier. At this point, it's mostly defunct, since we have the "Originally Released As" feature for cataloguing specific releases (which displays more cleanly in the artist chronology, too). However, it may still be used in certain cases where there isn't another album release that has the relevant date.
-    * For example, compilation album [The Funk McLovin Homestuck Experience](https://hsmusic.wiki/album/the-funk-mclovin-homestuck-experience/) uses `Original Date` for each track's earlier release on YouTube.
-    * The 2019 re-release of [One Year Older](https://hsmusic.wiki/album/one-year-older/) includes a bonus track, [it's good to see you again](https://hsmusic.wiki/track/its-good-to-see-you-again/). Rather than create a whole new album with basically the same structure, an additional group ("2019 release") was added with the single new track, which is `Original Date`'d as a *later* date than the rest of the album, placing it correctly in Erik Scheele's track chronology.
-    * All this is subject to change according to whatever form the upcoming "multiple releases" feature takes.
+  * This is pretty much exclusively for organization purpose on artist pages, where it doesn't make sense to chronologically position a track at one time if it was first released years earlier! At this point, `Date First Released` is more or less defunct, since we have the `Originally Released As` field for cataloguing specific releases (which displays more cleanly in the artist chronology, too). However, `Date First Released` may still be used in certain cases where there isn't another album release that has the relevant date.
+    * For example, compilation album [The Funk McLovin Homestuck Experience](https://hsmusic.wiki/album/the-funk-mclovin-homestuck-experience/) uses `Date First Released` for each track's earlier release on YouTube.
+    * The 2019 re-release of [One Year Older](https://hsmusic.wiki/album/one-year-older/) includes a bonus track, [it's good to see you again](https://hsmusic.wiki/track/its-good-to-see-you-again/). Rather than create a whole new album with basically the same structure, an additional track section ("2019 release") was added with the single new track, which has `Date First Released` set to a *later* date than the rest of the album. This way, the track is positioned correctly in Erik Scheele's track chronology.
+
+### Configuration & layout
 
 * `Cover Art Date`: date cover art created/added, if different from track/album release date
-  * If left unspecified, inherits from the track's *manually specified* `Date First Released`; or the album's `Default Track Cover Art Date` field; or the album's original date.
+  * Usually all the art for an album is released at the same time. If that time is different from when the album itself released, set the album's `Default Track Cover Art Date`. If specific tracks got their art added at a different time than the rest, use `Cover Art Date` on those tracks.
+  * If left unspecified, inherits from the track's *own* `Date First Released`; or the album's `Default Track Cover Art Date` field; or the album's original date.
   * This is displayed on track info pages only when different from the track's own release date.
-  * Guideline: This is mostly used for digital track art anthologies, where fans come together to add original artworks to an album released without art.
-  * Subject to change with upcoming "multiple artworks" feature.
-
 * `Cover Art File Extension`: corresponds to media file
-  * Don't include the "." separator: `Cover Art File Extension: png`, not `.png`.
+  * [Learn about file extension fields.](../common-fields.md#file-extension-fields)
   * If left unspecified, inherits from the album's `Track Art File Extension` field (*not* the album's `Cover Art File Extension`), or `jpg` by default.
-
 * `Has Cover Art`: disable to inherit from album cover art, or enable for one track with unique art amongst an album mostly without
   * If left unspecified, inherits from the album's `Has Track Art` field, which is true by default.
+  * Generally you'll only use this field if one or a few tracks uniquely lack (or have) cover art while most of the others do (or don't).
+
+### Content fields
 
+* `URLs`: web URLs for track playback or purchase
 * `Commentary`: commentary from track artists and others related
-  * [Learn more about formatting the Commentary field.](../guidelines/common-fields.md#commentary-field)
+  * [Learn how to format the Commentary field.](../guidelines/common-fields.md#commentary-field)
 * `Lyrics`: lyrics for vocals
-  * [Learn more about formatting the Lyrics field.](../guidelines/common-fields.md#lyrics)
+  * [Learn how to format the Lyrics field.](../guidelines/common-fields.md#lyrics)
   * [Read detailed guidelines on filling out lyrics for HSMusic.](../guidelines/lyrics.md)
-
 * `Additional Files`: bonus files associated with the track (there aren't any current uses of this field on the wiki)
 * `Sheet Music Files`: PDFs and other files containing sheet music for the track
 * `MIDI Project Files`: MIDI files for the track as well as DAW or tracker/sequencer project files
-  * These three fields share the same structured format - [learn more.](../guidelines/common-fields.md#additional-files-field)
+  * These three fields share the same structured format - [learn how to format fields like Additional Files.](../guidelines/common-fields.md#additional-files-field)
+
+### Relational fields
 
 * `Originally Released As`: links track to its earliest release
-  * Generally, this should be used instead of `Date Originally Released`, not alongside.
+  * Generally, don't combine with this `Date Originally Released` - use whichever is more appropriate.
   * Tracks with this field are displayed on the wiki as "re-releases", dimmed out a little in chronological listings (such as the list of tracks that an artist composed).
-  * Subject to change with upcoming "multiple releases" feature.
-
 * `Referenced Tracks`: links track to musical references, usually by leitmotif
-  * Guideline: List references by the order they are first present in the track; don't list an identical reference twice.
-  * Often these are listed on Bandcamp pages already, and can be sourced from there, especially if you aren't familiar with the musical material being referenced.
-
 * `Sampled Tracks`: links track to direct audio samples, often (but not exclusively) vocal clips
-  * This feature is mostly unused right now.
-
 * `Artists`: links track to its compositional artists
-  * May include parenthical descriptions, e.g. `'L. L. Zamenhof (lyrics)'`.
-  * Guideline: The line between "artists" and "contributors" is grey, and internally, it's an arbitrary distinction. "Artists" generally refers to people who played a major role in composing the track, while "contributors" tends to center on performance. See [`track:harlequin-rock-version`](https://hsmusic.wiki/track/harlequin-rock-version/) for an example.
-
 * `Contributors`: links track to other contributors, e.g. vocalists, performers
-  * May include parenthical descriptions, e.g. `'Willow Ascenzo (orchestra, choir)'`.
-  * See `Artists` for guidelines.
-
+  * [Learn about differentiating artists and contributors for HSMusic.](../guidelines/albums-and-tracks.md#differentiate-between-artists-and-contributors)
 * `Cover Artists`: links track to visual artists who created its artwork
-  * May include parenthical descriptions, e.g. `'Kait Linney (lines)'`.
-  * Visual and musical artists are the same document type, and some tracks actually have a shared composer and cover artist.
-  * Format subject to change with upcoming "multiple artworks" feature.
-
+  * All artist fields may include descriptions of the contribution in parentheses, e.g. `L. L. Zamenhof (lyrics)`, `Willow Ascenzo (orchestra, choir)`, `Kait Linney (lines)`.
 * `Art Tags`: links track to art tags representing characters or features present in its artwork
-  * Guideline: On HSMusic, we have two general categories of tags - characters and settings - and many tracks have both. Don't be afraid to create new tags for characters present in fanventures, etc (though we currently only tag *settings* from Homestuck proper).
-  * Format subject to change with upcoming "multiple artworks" feature.
diff --git a/guidelines/albums-and-tracks.md b/guidelines/albums-and-tracks.md
index c4cfbae..979e919 100644
--- a/guidelines/albums-and-tracks.md
+++ b/guidelines/albums-and-tracks.md
@@ -1,9 +1,13 @@
 # Album & Track Guidelines
 
-## `Name` field
-
 ### Name albums and tracks according to Bandcamp release
 
 Generally, HSMusic uses Bandcamp as the primary reference for album listings. Many albums which have been released across multiple platforms have slight differences in track naming (e.g. capitalization) — we prefer the naming on Bandcamp first. We also do our best not to editorialize here. Even if different tracks follow different capitalization rules seemingly arbitrarily, we leave that as-is!
 
 When there hasn't been a Bandcamp release, track and album naming can be a bit of a throw. Prefer another music streaming platform first, or whichever platform has the most complete track listing (e.g. if SoundCloud is missing a few tracks while YouTube has the full release, then pull names from YouTube). If the tracks haven't been officially released on *any* platforms, use whatever comes closest to "official" naming: titles as credited in video games, a title the artist passingly called the work when referencing it from some other commentary, etc.
+
+### Differentiate between artists and contributors
+
+(TODO. C'est blurry!)
+
+<!-- Old content: The line between "artists" and "contributors" is grey, and internally, it's an arbitrary distinction. "Artists" generally refers to people who played a major role in composing the track, while "contributors" tends to center on performance. See Harlequin (Rock Version) for an example. -->
diff --git a/guidelines/common-fields.md b/guidelines/common-fields.md
index ba98fec..42d0b54 100644
--- a/guidelines/common-fields.md
+++ b/guidelines/common-fields.md
@@ -1,7 +1,5 @@
 # Common Field Guidelines
 
-These guidelines are sorted alphabetically. Some link back to other sections in the guidelines area, so this is a good place to start browsing if you're just getting started with the data format and looking for details on any commonly occurring fields.
-
 ### `Additional Files` field
 
 Additional files are extra files pertinent to a particular album or track — usually ones which come with the album download or are "companion" files, like album booklets, desktop wallpapers, included lyrics files, etc. The format for `Additional Files` is a little more involved than most other fields. Here's an example:
@@ -145,6 +143,20 @@ Some examples of when you might manually set a directory:
 
 * In the most extreme cases, you may need to resort to violence. `『H☯MESTUCK VAP☯RWAVE 2016 RUH-RUH-RUH-ＲＥＭＩＸ』アンドレア・ヒューシー・グーグル翻訳` is not `h-omestuck-vap-rwave-2016-ruh-ruh-ruh` but `vaporwave-2016`, and `ＳジＢャＵンＲグＢル` is not an empty directory but `vaporwave-2016-track5`.
 
+### File extension fields
+
+HSMusic doesn't automatically detect the extension which corresponds to a media file it's going to display on the website (yet!). The *default* file extension used across the wiki is `jpg`, so if the media file being accessed is a PNG or GIF, specify it in a field like one of these:
+
+    Cover Art File Extension: png
+    Default Track Art File Extension: png
+    Banner Art File Extension: gif
+
+Note that these don't include the dot (`.`) before the extension.
+
+HSMusic only supports JPEG (in `jpg`, not `jpeg`), PNG and GIF image files for embedding right into pages. (You can still include other types of images or files and link to them in content like commentary or additional files.)
+
+There's not currently a way to specify a default image file extension across an entire wiki. ([See code issue #177.](https://github.com/hsmusic/hsmusic-wiki/issues/177))
+
 ### `Lyrics` field
 
 Lyrics are multiline strings, and they support `[[track:sburban-jungle]]`-style links just like the `Commentary` field. [Read more about formatting the Commentary field.](#commentary-field) (Just about all the same formatting applies here!)