diff --git a/Cargo.toml b/Cargo.toml
index 557b827..b7be417 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,10 +1,23 @@
 [package]
 name = "hyperbuild"
+description = "One-pass in-place HTML minifier written in Rust with advanced whitespace handling"
+license = "MIT"
+homepage = "https://github.com/wilsonzlin/hyperbuild"
+readme = "README.md"
+keywords = ["html", "compress", "minifier", "minify", "minification"]
+categories = ["compression", "command-line-utilities", "development-tools::build-utils", "web-programming"]
+repository = "https://github.com/wilsonzlin/hyperbuild.git"
 version = "0.0.1"
 authors = ["Wilson Lin <code@wilsonl.in>"]
 edition = "2018"
 
+[badges]
+maintenance = { status = "actively-developed" }
+
 [dependencies]
 phf = { version = "0.8.0", features = ["macros"] }
 cascade = "0.1.4"
 structopt = "0.3.5"
+
+[profile.release]
+panic = 'abort'
diff --git a/README.md b/README.md
index 6471ae9..31b08cd 100644
--- a/README.md
+++ b/README.md
@@ -2,8 +2,6 @@
 
 A fast one-pass in-place HTML minifier written in Rust with advanced whitespace handling.
 
-Currently in beta, working on documentation and tests. Issues and pull requests welcome! Guide below is currently WIP.
-
 ## Features
 
 - Minification is done in one pass with no backtracking or DOM/AST building.
@@ -26,6 +24,82 @@ hyperbuild has advanced whitespace minification that can allow strategies such a
 - Trim and collapse whitespace in content tags, as whitespace is collapsed anyway when rendered.
 - Remove whitespace in layout tags, which allows the use of inline layouts while keeping formatted code.
 
+#### Collapsing whitespace
+
+Reduce a sequence of whitespace characters in text nodes to a single space (U+0020).
+
+<table><thead><tr><th>Before<th>After<tbody><tr><td>
+
+```html
+<p>↵
+··The·quick·brown·fox↵
+··jumps·over·the·lazy↵
+··dog.↵
+</p>
+```
+
+<td>
+
+```html
+<p>·The·quick·brown·fox·jumps·over·the·lazy·dog.·</p>
+```
+
+</table>
+
+#### Destroying whole whitespace
+
+Remove any text nodes that only consist of whitespace characters.
+
+Especially useful when using `display: inline-block` so that whitespace between elements (e.g. indentation) does not alter layout and styling.
+
+<table><thead><tr><th>Before<th>After<tbody><tr><td>
+
+```html
+<ul>↵
+··<li>A</li>↵
+··<li>B</li>↵
+··<li>C</li>↵
+</ul>
+```
+
+<td>
+
+```html
+<ul><li>A</li><li>B</li><li>C</li></ul>
+```
+
+</table>
+
+#### Trimming whitespace
+
+Remove any whitespace from the start and end of a tag, if the first and/or last node is a text node.
+
+Useful when combined with whitespace collapsing.
+
+Other whitespace between text nodes and tags are not removed, as it is not recommended to mix non-formatting tags with raw text.
+
+Basically, a tag should only either contain text and [formatting tags](#formatting-tags), or only non-formatting tags.
+
+<table><thead><tr><th>Before<th>After<tbody><tr><td>
+
+```html
+<p>↵
+··Hey,·I·<em>just</em>·found↵
+··out·about·this·<strong>cool</strong>·website!↵
+··<div></div>↵
+</p>
+```
+
+<td>
+
+```html
+<p>Hey,·I·<em>just</em>·found↵
+··out·about·this·<strong>cool</strong>·website!↵
+··<div></div></p>
+```
+
+</table>
+
 ### Attributes
 
 Any entities in attribute values are decoded, and then the most optimal representation is calculated and used:
diff --git a/archive/child/blacklist.c b/archive/child/blacklist.c
deleted file mode 100644
index 12f570b..0000000
--- a/archive/child/blacklist.c
+++ /dev/null
@@ -1,92 +0,0 @@
-#include <hb/collection.h>
-#include <hb/rule.h>
-#include <hb/rune.h>
-
-static hb_map_tag_relations* hb_rule_tag_child_blacklist_map;
-
-void hb_rule_tag_child_blacklist_map_add_entries(hb_map_tag_relations* map)
-{
-	// <address>
-	hb_set_tag_names* address = hb_set_tag_names_create();
-	hb_rule_tag_heading_add_elems(address);
-	hb_rule_tag_sectioning_add_elems(address);
-	hb_set_tag_names_add_whole_literal(address, "address");
-	hb_set_tag_names_add_whole_literal(address, "header");
-	hb_set_tag_names_add_whole_literal(address, "footer");
-	hb_map_tag_relations_set_whole_literal(map, "address", address);
-
-	// <audio>
-	hb_set_tag_names* audio = hb_set_tag_names_create();
-	hb_rule_tag_media_add_elems(audio);
-	hb_map_tag_relations_set_whole_literal(map, "audio", audio);
-
-	// <dfn>
-	hb_set_tag_names* dfn = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(dfn, "dfn");
-	hb_map_tag_relations_set_whole_literal(map, "dfn", dfn);
-
-	// <dt>
-	hb_set_tag_names* dt = hb_set_tag_names_create();
-	hb_rule_tag_heading_add_elems(dt);
-	hb_rule_tag_sectioning_add_elems(dt);
-	hb_set_tag_names_add_whole_literal(dt, "header");
-	hb_set_tag_names_add_whole_literal(dt, "footer");
-	hb_map_tag_relations_set_whole_literal(map, "dt", dt);
-
-	// <footer>
-	hb_set_tag_names* footer = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(footer, "header");
-	hb_set_tag_names_add_whole_literal(footer, "footer");
-	hb_map_tag_relations_set_whole_literal(map, "footer", footer);
-
-	// <form>
-	hb_set_tag_names* form = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(form, "form");
-	hb_map_tag_relations_set_whole_literal(map, "form", form);
-
-	// <header>
-	hb_set_tag_names* header = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(header, "header");
-	hb_set_tag_names_add_whole_literal(header, "footer");
-	hb_map_tag_relations_set_whole_literal(map, "header", header);
-
-	// <label>
-	hb_set_tag_names* label = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(label, "label");
-	hb_map_tag_relations_set_whole_literal(map, "label", label);
-
-	// <progress>
-	hb_set_tag_names* progress = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(progress, "progress");
-	hb_map_tag_relations_set_whole_literal(map, "progress", progress);
-
-	// <th>
-	hb_set_tag_names* th = hb_set_tag_names_create();
-	hb_rule_tag_heading_add_elems(th);
-	hb_rule_tag_sectioning_add_elems(th);
-	hb_set_tag_names_add_whole_literal(th, "header");
-	hb_set_tag_names_add_whole_literal(th, "footer");
-	hb_map_tag_relations_set_whole_literal(map, "th", th);
-
-	// <video>
-	hb_set_tag_names* video = hb_set_tag_names_create();
-	hb_rule_tag_media_add_elems(video);
-	hb_map_tag_relations_set_whole_literal(map, "video", video);
-}
-
-void hb_rule_tag_child_blacklist_init(void)
-{
-	hb_rule_tag_child_blacklist_map = hb_map_tag_relations_create();
-	hb_rule_tag_child_blacklist_map_add_entries(
-		hb_rule_tag_child_blacklist_map);
-}
-
-// Check if a parent is allowed to have a specific child, based on the
-// blacklist.
-bool hb_rule_tag_child_blacklist_allowed(nh_view_str* parent,
-					 nh_view_str* child)
-{
-	hb_set_tag_names* set = hb_map_tag_relations_get(
-		hb_rule_tag_child_blacklist_map, parent);
-	return set == NULL || !hb_set_tag_names_has(set, child);
-}
diff --git a/archive/child/whitelist.c b/archive/child/whitelist.c
deleted file mode 100644
index b6aab16..0000000
--- a/archive/child/whitelist.c
+++ /dev/null
@@ -1,106 +0,0 @@
-#include <hb/collection.h>
-#include <hb/rule.h>
-#include <hb/rune.h>
-
-static hb_map_tag_relations* hb_rule_tag_child_whitelist_map;
-
-void hb_rule_tag_child_whitelist_map_add_entries(hb_map_tag_relations* map)
-{
-	// <colgroup>
-	hb_set_tag_names* colgroup = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(colgroup, "col");
-	hb_map_tag_relations_set_whole_literal(map, "colgroup", colgroup);
-
-	// <datalist>
-	hb_set_tag_names* datalist = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(datalist, "option");
-	hb_map_tag_relations_set_whole_literal(map, "datalist", datalist);
-
-	// <dl>
-	hb_set_tag_names* dl = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(dl, "dt");
-	hb_set_tag_names_add_whole_literal(dl, "dd");
-	hb_map_tag_relations_set_whole_literal(map, "dl", dl);
-
-	// <hgroup>
-	hb_set_tag_names* hgroup = hb_set_tag_names_create();
-	hb_rule_tag_heading_add_elems(hgroup);
-	hb_map_tag_relations_set_whole_literal(map, "hgroup", hgroup);
-
-	// <ol>
-	hb_set_tag_names* ol = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(ol, "li");
-	hb_map_tag_relations_set_whole_literal(map, "ol", ol);
-
-	// <optgroup>
-	hb_set_tag_names* optgroup = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(optgroup, "option");
-	hb_map_tag_relations_set_whole_literal(map, "optgroup", optgroup);
-
-	// <picture>
-	hb_set_tag_names* picture = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(picture, "source");
-	hb_set_tag_names_add_whole_literal(picture, "img");
-	hb_map_tag_relations_set_whole_literal(map, "picture", picture);
-
-	// <select>
-	hb_set_tag_names* select = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(select, "optgroup");
-	hb_set_tag_names_add_whole_literal(select, "option");
-	hb_map_tag_relations_set_whole_literal(map, "select", select);
-
-	// <table>
-	hb_set_tag_names* table = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(table, "caption");
-	hb_set_tag_names_add_whole_literal(table, "colgroup");
-	hb_set_tag_names_add_whole_literal(table, "col");
-	hb_set_tag_names_add_whole_literal(table, "thead");
-	hb_set_tag_names_add_whole_literal(table, "tbody");
-	hb_set_tag_names_add_whole_literal(table, "tfoot");
-	hb_set_tag_names_add_whole_literal(table, "tr");
-	hb_map_tag_relations_set_whole_literal(map, "table", table);
-
-	// <tbody>
-	hb_set_tag_names* tbody = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(tbody, "tr");
-	hb_map_tag_relations_set_whole_literal(map, "tbody", tbody);
-
-	// <tfoot>
-	hb_set_tag_names* tfoot = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(tfoot, "tr");
-	hb_map_tag_relations_set_whole_literal(map, "tfoot", tfoot);
-
-	// <thead>
-	hb_set_tag_names* thead = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(thead, "tr");
-	hb_map_tag_relations_set_whole_literal(map, "thead", thead);
-
-	// <tr>
-	hb_set_tag_names* tr = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(tr, "td");
-	hb_set_tag_names_add_whole_literal(tr, "th");
-	hb_set_tag_names_add_whole_literal(tr, "template");
-	hb_set_tag_names_add_whole_literal(tr, "script");
-	hb_map_tag_relations_set_whole_literal(map, "tr", tr);
-
-	// <ul>
-	hb_set_tag_names* ul = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(ul, "li");
-	hb_map_tag_relations_set_whole_literal(map, "ul", ul);
-}
-
-void hb_rule_tag_child_whitelist_init(void)
-{
-	hb_rule_tag_child_whitelist_map = hb_map_tag_relations_create();
-	hb_rule_tag_child_whitelist_map_add_entries(
-		hb_rule_tag_child_whitelist_map);
-}
-
-// Check if a parent is allowed to have a specific child.
-bool hb_rule_tag_child_whitelist_allowed(nh_view_str* parent,
-					 nh_view_str* child)
-{
-	hb_set_tag_names* set = hb_map_tag_relations_get(
-		hb_rule_tag_child_whitelist_map, parent);
-	return set == NULL || hb_set_tag_names_has(set, child);
-}
diff --git a/archive/old.readme.md b/archive/old.readme.md
deleted file mode 100644
index 4865976..0000000
--- a/archive/old.readme.md
+++ /dev/null
@@ -1,215 +0,0 @@
-#### Beginning and end
-
-```html
-<p>↵
-··The·quick·brown·fox↵
-</p>
-```
-
-#### Between text and tags
-
-```html
-<p>The·quick·brown·fox·<strong>jumps</strong>·over·the·lazy·dog.</p>
-```
-
-#### Contiguous
-
-```html
-<select>↵
-··<option>Jan:·········1</option>↵
-··<option>Feb:········10</option>↵
-··<option>Mar:·······100</option>↵
-··<option>Apr:······1000</option>↵
-··<option>May:·····10000</option>↵
-··<option>Jun:····100000</option>↵
-</select>
-```
-
-#### Whole text
-
-```html
-<p>↵
-···↵
-</p>
-```
-
-### Tag classification
-
-|Type|Content|
-|---|---|
-|Formatting tags|Text nodes|
-|Content tags|Formatting tags, text nodes|
-|Layout tags|Layout tags, content tags|
-|Content-first tags|Content of content tags or layout tags (but not both)|
-
-#### Specific tags
-
-Tags not in one of the categories below are **specific tags**.
-
-#### Formatting tags
-
-```html
-<strong> moat </strong>
-```
-
-#### Content tags
-
-```html
-<p>Some <strong>content</strong></p>
-```
-
-#### Content-first tags
-
-```html
-<li>Anthony</li>
-```
-
-```html
-<li>
-  <div>
-  </div>
-</li>
-```
-
-#### Layout tags
-
-```html
-<div>
-  <div></div>
-</div>
-```
-
-### Options
-
-For options that have a list of tags as their value, the tags should be separated by a comma.
-
-An `*` (asterisk, U+002A) can be used to represent the complete set of possible tags. Providing no value represents the empty set.
-Both values essentially fully enables or disables the option.
-
-For brevity, hyperbuild has built-in sets of tags that can be used in place of declaring all their members; they begin with a `$` sign:
-
-|Name|Tags|Source|
-|---|---|---|
-|`$content`|`address`, `audio`, `button`, `canvas`, `caption`, `figcaption`, `h1`, `h2`, `h3`, `h4`, `h5`, `h6`, `legend`, `meter`, `object`, `option`, `p`, `summary`, `textarea`, `video`|[contenttags.c](src/main/c/rule/tag/contenttags.c)|
-|`$contentfirst`|`dd`, `details`, `dt`, `iframe`, `label`, `li`, `noscript`, `output`, `progress`, `slot`, `td`, `template`, `th`|[contentfirsttags.c](src/main/c/rule/tag/contentfirsttags.c)|
-|`$formatting`|`a`, `abbr`, `b`, `bdi`, `bdo`, `cite`, `data`, `del`, `dfn`, `em`, `i`, `ins`, `kbd`, `mark`, `q`, `rp`, `rt`, `rtc`, `ruby`, `s`, `samp`, `small`, `span`, `strong`, `sub`, `sup`, `time`, `u`, `var`, `wbr`|[formattingtags.c](src/main/c/rule/tag/formattingtags.c)|
-|`$layout`|`blockquote`, `body`, `colgroup`, `datalist`, `dialog`, `div`, `dl`, `fieldset`, `figure`, `footer`, `form`, `head`, `header`, `hgroup`, `html`, `main`, `map`, `menu`, `nav`, `ol`, `optgroup`, `picture`, `section`, `select`, `table`, `tbody`, `tfoot`, `thead`, `tr`, `ul`|[layouttags.c](src/main/c/rule/tag/layouttags.c)|
-|`$specific`|All [SVG tags](src/main/c/rule/tag/svgtags.c), `area`, `base`, `br`, `code`, `col`, `embed`, `hr`, `img`, `input`, `param`, `pre`, `script`, `source`, `track`|[specifictags.c](src/main/c/rule/tag/specifictags.c)|
-|`$heading`|`hgroup`, `h1`, `h2`, `h3`, `h4`, `h5`, `h6`|[headingtags.c](src/main/c/rule/tag/headingtags.c)|
-|`$media`|`audio`, `video`|[mediatags.c](src/main/c/rule/tag/mediatags.c)|
-|`$sectioning`|`article`, `aside`, `nav`, `section`|[sectioningtags.c](src/main/c/rule/tag/sectioningtags.c)|
-|`$void`|`area`, `base`, `br`, `col`, `embed`, `hr`, `img`, `input`, `keygen`, `link`, `meta`, `param`, `source`, `track`, `wbr`|[voidtags.c](src/main/c/rule/tag/voidtags.c)|
-|`$wss`|`pre`, `code`|[wsstags.c](src/main/c/rule/tag/wsstags.c)|
-
-As an example, for `--MXcollapseWhitespace`, here are some possible values:
-
-|Arguments|Description|
-|---|---|
-|`--MXcollapseWhitespace $wss`|Collapse whitespace in all tags except `$wss` ones|
-|`--MXcollapseWhitespace $content,$wss`|Collapse whitespace in all tags except `$content` and `$wss` ones|
-|`--MXcollapseWhitespace $content,$wss,dd`|Collapse whitespace in all tags except `$content` and `$wss` ones, as well as the `dd` tag|
-|`--MXcollapseWhitespace sup,dd`|Collapse whitespace in all tags except `sup` and `dd`|
-|`--MXcollapseWhitespace`|Collapse whitespace in all tags|
-|`--MXcollapseWhitespace *`|Don't collapse whitespace in any tag|
-
-#### `--MXcollapseWhitespace $wss`
-
-Reduce a sequence of whitespace characters in text nodes to a single space (U+0020), unless they are a child of the tags specified by this option.
-
-<table><thead><tr><th>Before<th>After<tbody><tr><td>
-
-```html
-<p>↵
-··The·quick·brown·fox↵
-··jumps·over·the·lazy↵
-··dog.↵
-</p>
-```
-
-<td>
-
-```html
-<p>·The·quick·brown·fox·jumps·over·the·lazy·dog.·</p>
-```
-
-</table>
-
-#### `--MXdestroyWholeWhitespace $wss,$content,$formatting`
-
-Remove any text nodes that only consist of whitespace characters, unless they are a child of the tags specified by this option.
-
-Especially useful when using `display: inline-block` so that whitespace between elements (e.g. indentation) does not alter layout and styling.
-
-<table><thead><tr><th>Before<th>After<tbody><tr><td>
-
-```html
-<div>↵
-··<h1></h1>↵
-··<ul></ul>↵
-··A·quick·<strong>brown</strong>·<em>fox</em>.↵
-</div>
-```
-
-<td>
-
-```html
-<div><h1></h1><ul></ul>↵
-··A·quick·<strong>brown</strong><em>fox</em>.↵
-</div>
-```
-
-</table>
-
-#### `--MXtrimWhitespace $wss,$formatting`
-
-Remove any whitespace from the start and end of a tag, if the first and/or last node is a text node, unless the tag is one of the tags specified by this option.
-
-Useful when combined with whitespace collapsing.
-
-Other whitespace between text nodes and tags are not removed, as it is not recommended to mix non-formatting tags with raw text.
-
-Basically, a tag should only either contain text and [formatting tags](#formatting-tags), or only non-formatting tags.
-
-<table><thead><tr><th>Before<th>After<tbody><tr><td>
-
-```html
-<p>↵
-··Hey,·I·<em>just</em>·found↵
-··out·about·this·<strong>cool</strong>·website!↵
-··<div></div>↵
-</p>
-```
-
-<td>
-
-```html
-<p>Hey,·I·<em>just</em>·found↵
-··out·about·this·<strong>cool</strong>·website!↵
-··<div></div></p>
-```
-
-</table>
-
-#### `--MXtrimClassAttribute`
-
-Don't trim and collapse whitespace in `class` attribute values.
-
-<table><thead><tr><th>Before<th>After<tbody><tr><td>
-
-```html
-<div class="
-  hi
-  lo
-  a b c
-    d e
-  f   g
-"></div>
-```
-
-<td>
-
-```html
-<div class="hi lo a b c d e f g"></div>
-```
-
-</table>
diff --git a/archive/parent/blacklist.c b/archive/parent/blacklist.c
deleted file mode 100644
index 2cf3de9..0000000
--- a/archive/parent/blacklist.c
+++ /dev/null
@@ -1,20 +0,0 @@
-#include <hb/collection.h>
-#include <hb/rule.h>
-#include <hb/rune.h>
-
-void hb_rule_tag_parent_blacklist_init(void)
-{
-	// Don't do anything. This rule is currently unused.
-}
-
-// Check if a child is allowed to have a specific parent, based on the
-// blacklist.
-bool hb_rule_tag_parent_blacklist_allowed(nh_view_str* child,
-					  nh_view_str* parent)
-{
-	// Since this rule is currently not being used, directly allow without
-	// any checks.
-	(void) child;
-	(void) parent;
-	return true;
-}
diff --git a/archive/parent/whitelist.c b/archive/parent/whitelist.c
deleted file mode 100644
index 4a39f56..0000000
--- a/archive/parent/whitelist.c
+++ /dev/null
@@ -1,151 +0,0 @@
-#include <hb/collection.h>
-#include <hb/rule.h>
-#include <hb/rune.h>
-
-static hb_map_tag_relations* hb_rule_tag_parent_whitelist_map;
-
-void hb_rule_tag_parent_whitelist_map_add_entries(hb_map_tag_relations* map)
-{
-	// <caption>
-	hb_set_tag_names* caption = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(caption, "table");
-	hb_map_tag_relations_set_whole_literal(map, "caption", caption);
-
-	// <col>
-	hb_set_tag_names* col = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(col, "table");
-	hb_set_tag_names_add_whole_literal(col, "colgroup");
-	hb_map_tag_relations_set_whole_literal(map, "col", col);
-
-	// <colgroup>
-	hb_set_tag_names* colgroup = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(colgroup, "table");
-	hb_map_tag_relations_set_whole_literal(map, "colgroup", colgroup);
-
-	// <dd>
-	hb_set_tag_names* dd = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(dd, "dl");
-	hb_map_tag_relations_set_whole_literal(map, "dd", dd);
-
-	// <dt>
-	hb_set_tag_names* dt = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(dt, "dl");
-	hb_map_tag_relations_set_whole_literal(map, "dt", dt);
-
-	// <figcaption>
-	hb_set_tag_names* figcaption = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(figcaption, "figure");
-	hb_map_tag_relations_set_whole_literal(map, "figcaption", figcaption);
-
-	// <legend>
-	hb_set_tag_names* legend = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(legend, "fieldset");
-	hb_map_tag_relations_set_whole_literal(map, "legend", legend);
-
-	// <li>
-	hb_set_tag_names* li = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(li, "ul");
-	hb_set_tag_names_add_whole_literal(li, "ol");
-	hb_set_tag_names_add_whole_literal(li, "menu");
-	hb_map_tag_relations_set_whole_literal(map, "li", li);
-
-	// <optgroup>
-	hb_set_tag_names* optgroup = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(optgroup, "select");
-	hb_map_tag_relations_set_whole_literal(map, "optgroup", optgroup);
-
-	// <option>
-	hb_set_tag_names* option = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(option, "select");
-	hb_set_tag_names_add_whole_literal(option, "optgroup");
-	hb_set_tag_names_add_whole_literal(option, "datalist");
-	hb_map_tag_relations_set_whole_literal(map, "option", option);
-
-	// <param>
-	hb_set_tag_names* param = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(param, "object");
-	hb_map_tag_relations_set_whole_literal(map, "param", param);
-
-	// <rp>
-	hb_set_tag_names* rp = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(rp, "ruby");
-	hb_map_tag_relations_set_whole_literal(map, "rp", rp);
-
-	// <rt>
-	hb_set_tag_names* rt = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(rt, "ruby");
-	hb_map_tag_relations_set_whole_literal(map, "rt", rt);
-
-	// <rtc>
-	hb_set_tag_names* rtc = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(rtc, "ruby");
-	hb_map_tag_relations_set_whole_literal(map, "rtc", rtc);
-
-	// <summary>
-	hb_set_tag_names* summary = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(summary, "details");
-	hb_map_tag_relations_set_whole_literal(map, "summary", summary);
-
-	// <source>
-	hb_set_tag_names* source = hb_set_tag_names_create();
-	hb_rule_tag_media_add_elems(source);
-	hb_set_tag_names_add_whole_literal(source, "picture");
-	hb_map_tag_relations_set_whole_literal(map, "source", source);
-
-	// <track>
-	hb_set_tag_names* track = hb_set_tag_names_create();
-	hb_rule_tag_media_add_elems(track);
-	hb_map_tag_relations_set_whole_literal(map, "track", track);
-
-	// <tbody>
-	hb_set_tag_names* tbody = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(tbody, "table");
-	hb_map_tag_relations_set_whole_literal(map, "tbody", tbody);
-
-	// <td>
-	hb_set_tag_names* td = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(td, "tr");
-	hb_map_tag_relations_set_whole_literal(map, "td", td);
-
-	// <tfoot>
-	hb_set_tag_names* tfoot = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(tfoot, "table");
-	hb_map_tag_relations_set_whole_literal(map, "tfoot", tfoot);
-
-	// <th>
-	hb_set_tag_names* th = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(th, "tr");
-	hb_map_tag_relations_set_whole_literal(map, "th", th);
-
-	// <thead>
-	hb_set_tag_names* thead = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(thead, "table");
-	hb_map_tag_relations_set_whole_literal(map, "thead", thead);
-
-	// <tr>
-	hb_set_tag_names* tr = hb_set_tag_names_create();
-	hb_set_tag_names_add_whole_literal(tr, "table");
-	hb_set_tag_names_add_whole_literal(tr, "thead");
-	hb_set_tag_names_add_whole_literal(tr, "tbody");
-	hb_set_tag_names_add_whole_literal(tr, "tfoot");
-	hb_map_tag_relations_set_whole_literal(map, "tr", tr);
-
-	// <template>
-	// Should be <body>, <frameset>, <head>, <dl>, <colgroup>, but ignoring.
-}
-
-void hb_rule_tag_parent_whitelist_init(void)
-{
-	hb_rule_tag_parent_whitelist_map = hb_map_tag_relations_create();
-	hb_rule_tag_parent_whitelist_map_add_entries(
-		hb_rule_tag_parent_whitelist_map);
-}
-
-// Check if a child is allowed to have a specific parent.
-bool hb_rule_tag_parent_whitelist_allowed(nh_view_str* child,
-					  nh_view_str* parent)
-{
-	hb_set_tag_names* set = hb_map_tag_relations_get(
-		hb_rule_tag_parent_whitelist_map, child);
-	return set == NULL || hb_set_tag_names_has(set, parent);
-}
diff --git a/notes/Tag types.md b/notes/Tag types.md
new file mode 100644
index 0000000..0937b38
--- /dev/null
+++ b/notes/Tag types.md	
@@ -0,0 +1,41 @@
+# Tag types
+
+|Type|Expected content|
+|---|---|
+|Formatting tags|Text nodes.|
+|Content tags|Formatting tags, text nodes.|
+|Layout tags|Layout tags, content tags.|
+|Content-first tags|Content of content tags or layout tags (but not both).|
+
+## Formatting tags
+
+```html
+<strong> moat </strong>
+```
+
+## Content tags
+
+```html
+<p>Some <strong>content</strong></p>
+```
+
+## Content-first tags
+
+```html
+<li>Anthony</li>
+```
+
+```html
+<li>
+  <div>
+  </div>
+</li>
+```
+
+## Layout tags
+
+```html
+<div>
+  <div></div>
+</div>
+```
diff --git a/src/spec/tag/formatting.rs b/src/spec/tag/formatting.rs
index 0360dae..f65c023 100644
--- a/src/spec/tag/formatting.rs
+++ b/src/spec/tag/formatting.rs
@@ -1,6 +1,7 @@
 use ::phf::{phf_set, Set};
 
-// Difference to MDN's inline text semantics list: -br, +del, +ins.
+// Sourced from https://developer.mozilla.org/en-US/docs/Web/HTML/Element#Inline_text_semantics.
+// Differences to tags listed in table at above URL: -br, +del, +ins.
 pub static FORMATTING_TAGS: Set<&'static [u8]> = phf_set! {
 	b"a",
 	b"abbr",
diff --git a/src/spec/tag/heading.rs b/src/spec/tag/heading.rs
deleted file mode 100644
index b97faeb..0000000
--- a/src/spec/tag/heading.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-use ::phf::{phf_set, Set};
-
-pub static HEADING_TAGS: Set<&'static [u8]> = phf_set! {
-	b"hgroup",
-	b"h1",
-	b"h2",
-	b"h3",
-	b"h4",
-	b"h5",
-	b"h6",
-};
diff --git a/src/spec/tag/html.rs b/src/spec/tag/html.rs
deleted file mode 100644
index bd4d816..0000000
--- a/src/spec/tag/html.rs
+++ /dev/null
@@ -1,148 +0,0 @@
-use ::phf::{phf_set, Set};
-
-// Sourced from https://developer.mozilla.org/en-US/docs/Web/HTML/Element at 2018-07-01T05:55:00Z.
-pub static HTML_TAGS: Set<&'static [u8]> = phf_set! {
-	b"a",
-	b"abbr",
-	b"acronym",
-	b"address",
-	b"applet",
-	b"area",
-	b"article",
-	b"aside",
-	b"audio",
-	b"b",
-	b"basefont",
-	b"bdi",
-	b"bdo",
-	b"bgsound",
-	b"big",
-	b"blink",
-	b"blockquote",
-	b"body",
-	b"br",
-	b"button",
-	b"canvas",
-	b"caption",
-	b"center",
-	b"cite",
-	b"code",
-	b"col",
-	b"colgroup",
-	b"command",
-	b"content",
-	b"data",
-	b"datalist",
-	b"dd",
-	b"del",
-	b"details",
-	b"dfn",
-	b"dialog",
-	b"dir",
-	b"div",
-	b"dl",
-	b"dt",
-	b"element",
-	b"em",
-	b"embed",
-	b"fieldset",
-	b"figcaption",
-	b"figure",
-	b"font",
-	b"footer",
-	b"form",
-	b"frame",
-	b"frameset",
-	b"h1",
-	b"h2",
-	b"h3",
-	b"h4",
-	b"h5",
-	b"h6",
-	b"head",
-	b"header",
-	b"hgroup",
-	b"hr",
-	b"html",
-	b"i",
-	b"iframe",
-	b"image",
-	b"img",
-	b"input",
-	b"ins",
-	b"isindex",
-	b"kbd",
-	b"keygen",
-	b"label",
-	b"legend",
-	b"li",
-	b"link",
-	b"listing",
-	b"main",
-	b"map",
-	b"mark",
-	b"marquee",
-	b"menu",
-	b"menuitem",
-	b"meta",
-	b"meter",
-	b"multicol",
-	b"nav",
-	b"nextid",
-	b"nobr",
-	b"noembed",
-	b"noframes",
-	b"noscript",
-	b"object",
-	b"ol",
-	b"optgroup",
-	b"option",
-	b"output",
-	b"p",
-	b"param",
-	b"picture",
-	b"plaintext",
-	b"pre",
-	b"progress",
-	b"q",
-	b"rp",
-	b"rt",
-	b"rtc",
-	b"ruby",
-	b"s",
-	b"samp",
-	b"script",
-	b"section",
-	b"select",
-	b"shadow",
-	b"slot",
-	b"small",
-	b"source",
-	b"spacer",
-	b"span",
-	b"strike",
-	b"strong",
-	b"style",
-	b"sub",
-	b"summary",
-	b"sup",
-	b"table",
-	b"tbody",
-	b"td",
-	b"template",
-	b"textarea",
-	b"tfoot",
-	b"th",
-	b"thead",
-	b"time",
-	b"title",
-	b"tr",
-	b"track",
-	b"tt",
-	b"u",
-	b"ul",
-	b"var",
-	b"video",
-	b"wbr",
-	b"xmp",
-};
diff --git a/src/spec/tag/layout.rs b/src/spec/tag/layout.rs
index 242f84f..80bfd4a 100644
--- a/src/spec/tag/layout.rs
+++ b/src/spec/tag/layout.rs
@@ -1,12 +1,8 @@
 use ::phf::{phf_set, Set};
 
 pub static LAYOUT_TAGS: Set<&'static [u8]> = phf_set! {
-    // Sectioning tags.
 	b"article",
 	b"aside",
-	b"nav",
-	b"section",
-	// Other tags.
 	b"blockquote",
 	b"body",
 	b"colgroup",
@@ -25,9 +21,11 @@ pub static LAYOUT_TAGS: Set<&'static [u8]> = phf_set! {
 	b"main",
 	b"map",
 	b"menu",
+	b"nav",
 	b"ol",
 	b"optgroup",
 	b"picture",
+	b"section",
 	b"select",
 	b"table",
 	b"tbody",
diff --git a/src/spec/tag/media.rs b/src/spec/tag/media.rs
deleted file mode 100644
index 4ea955b..0000000
--- a/src/spec/tag/media.rs
+++ /dev/null
@@ -1,6 +0,0 @@
-use ::phf::{phf_set, Set};
-
-pub static MEDIA_TAGS: Set<&'static [u8]> = phf_set! {
-	b"audio",
-	b"video",
-};
diff --git a/src/spec/tag/sectioning.rs b/src/spec/tag/sectioning.rs
deleted file mode 100644
index a01ee10..0000000
--- a/src/spec/tag/sectioning.rs
+++ /dev/null
@@ -1,9 +0,0 @@
-use ::phf::{phf_set, Set};
-
-pub static SECTIONING_TAGS: Set<&'static [u8]> = phf_set! {
-    // Also used by layout tags.
-	b"article",
-	b"aside",
-	b"nav",
-	b"section",
-};
diff --git a/src/spec/tag/specific.rs b/src/spec/tag/specific.rs
deleted file mode 100644
index 5b4d57f..0000000
--- a/src/spec/tag/specific.rs
+++ /dev/null
@@ -1,19 +0,0 @@
-use ::phf::{phf_set, Set};
-
-// Does not include SVG tags.
-pub static SPECIFIC_HTML_TAGS: Set<&'static [u8]> = phf_set! {
-	b"area",
-	b"base",
-	b"br",
-	b"code", // Reason: unlikely to want to minify.
-	b"col",
-	b"embed",
-	b"hr",
-	b"img",
-	b"input",
-	b"param",
-	b"pre", // Reason: unlikely to want to minify.
-	b"script",
-	b"source",
-	b"track",
-};
diff --git a/src/spec/tag/svg.rs b/src/spec/tag/svg.rs
deleted file mode 100644
index dcbe0e3..0000000
--- a/src/spec/tag/svg.rs
+++ /dev/null
@@ -1,95 +0,0 @@
-use ::phf::{phf_set, Set};
-
-// Sourced from https://developer.mozilla.org/en-US/docs/Web/SVG/Element at 2018-08-04T03:50:00Z.
-pub static SVG_TAGS: Set<&'static [u8]> = phf_set! {
-	b"a",
-	b"altGlyph",
-	b"altGlyphDef",
-	b"altGlyphItem",
-	b"animate",
-	b"animateColor",
-	b"animateMotion",
-	b"animateTransform",
-	b"circle",
-	b"clipPath",
-	b"color-profile",
-	b"cursor",
-	b"defs",
-	b"desc",
-	b"discard",
-	b"ellipse",
-	b"feBlend",
-	b"feColorMatrix",
-	b"feComponentTransfer",
-	b"feComposite",
-	b"feConvolveMatrix",
-	b"feDiffuseLighting",
-	b"feDisplacementMap",
-	b"feDistantLight",
-	b"feDropShadow",
-	b"feFlood",
-	b"feFuncA",
-	b"feFuncB",
-	b"feFuncG",
-	b"feFuncR",
-	b"feGaussianBlur",
-	b"feImage",
-	b"feMerge",
-	b"feMergeNode",
-	b"feMorphology",
-	b"feOffset",
-	b"fePointLight",
-	b"feSpecularLighting",
-	b"feSpotLight",
-	b"feTile",
-	b"feTurbulence",
-	b"filter",
-	b"font-face-format",
-	b"font-face-name",
-	b"font-face-src",
-	b"font-face-uri",
-	b"font-face",
-	b"font",
-	b"foreignObject",
-	b"g",
-	b"glyph",
-	b"glyphRef",
-	b"hatch",
-	b"hatchpath",
-	b"hkern",
-	b"image",
-	b"line",
-	b"linearGradient",
-	b"marker",
-	b"mask",
-	b"mesh",
-	b"meshgradient",
-	b"meshpatch",
-	b"meshrow",
-	b"metadata",
-	b"missing-glyph",
-	b"mpath",
-	b"path",
-	b"pattern",
-	b"polygon",
-	b"polyline",
-	b"radialGradient",
-	b"rect",
-	b"script",
-	b"set",
-	b"solidcolor",
-	b"stop",
-	b"style",
-	b"svg",
-	b"switch",
-	b"symbol",
-	b"text",
-	b"textPath",
-	b"title",
-	b"tref",
-	b"tspan",
-	b"unknown",
-	b"use",
-	b"view",
-	b"vkern",
-};
diff --git a/src/spec/tag/wss.rs b/src/spec/tag/wss.rs
index a034818..90a434f 100644
--- a/src/spec/tag/wss.rs
+++ b/src/spec/tag/wss.rs
@@ -1,6 +1,6 @@
-// "WSS" stands for whitespace-sensitive.
 use ::phf::{phf_set, Set};
 
+// "WSS" stands for whitespace-sensitive.
 pub static WSS_TAGS: Set<&'static [u8]> = phf_set! {
 	b"code",
 	b"pre",