Missing HTML Terms — AI Knowledge-Base Gap Analysis

Purpose of this file. The current curriculum in terms/level_01 … terms/level_10 defines 52 terms (see _meta/html_terms_zero_to_hero.md). Reviewing it as a junior engineer trying to learn HTML from these files alone, I hit gaps: concepts that the existing docs use, assume, or reference in prose but never define as their own term. This file catalogs those gaps so an AI can generate the missing term docs and make the knowledge base self-contained.

How to read this file.

Section 1 — the critical gaps (concepts used everywhere but never taught).

Section 2 — the full list of missing terms, grouped by the level they belong to. Each row is shaped to drop straight into the term-doc template: it names the prerequisites and related terms so the ## 1. Prerequisites and ## 7. Related Terms sections can be filled in automatically.

Section 3 — the relationship map (dependency graph) between missing terms and existing terms.

Section 4 — suggested generation priority.

Evidence method. "Gap" = concept appears in prose/code of ≥1 existing term file but has no dedicated terms/level_XX/<term>.md. Also includes concepts a junior learner would need to bridge between levels to achieve smooth progressive learning.

1. Critical Gaps (used pervasively, never defined)

These block comprehension the most because existing lessons rely on them without explanation.

Gap	Evidence (files mentioning it)	Why it blocks learning
Block-level vs Inline elements	`div.md` calls itself "block container", `span.md` says "inline container", `br_hr.md` mentions line breaks vs thematic breaks, `strong_em.md` uses inline styling	The single most important HTML layout concept is never defined. A learner sees "block" and "inline" on every page but has no term explaining why `<div>` takes the full width and `<span>` doesn't.
Void Elements (Self-closing tags)	`meta.md`, `link.md`, `input.md`, `img.md`, `br_hr.md` — all mention "void element" in passing	Five existing term docs call tags "void elements" but the concept of a void element is never defined. A learner doesn't know why some tags lack closing tags.
`name` Attribute	`input.md` calls it "absolutely required", `form.md` references it, `select_option.md` and `textarea.md` use it	The `name` attribute is the key mechanism for form submission (key-value pairing) and radio button grouping. It's used in every form example but never taught.
`value` Attribute	Used in `input.md`, `select_option.md`, `button.md` radio/checkbox examples	The `value` attribute determines what data actually gets sent to the server. It is paired with `name` in every form but never defined.
`required`, `placeholder`, `disabled` Attributes	`input.md` uses `placeholder` in every example, `form.md` mentions `required`	These are the most commonly-used form validation/UX attributes. A learner sees `placeholder="First Name"` in examples but has no term explaining what these attributes do.
`defer` & `async` Attributes (on `<script>`)	`script.md` teaches the `defer` attribute as the FIX for render-blocking but never gives it a dedicated term	The `<script>` doc tells learners to use `defer` to fix a critical mistake, but the `defer` and `async` loading strategies are never formally defined.
Character Encoding / `charset="UTF-8"`	`meta.md` calls it "the most important meta tag"	Every `<meta>` example starts with `charset="UTF-8"` but the concept of character encoding is never explained. A learner doesn't know what UTF-8 is or why it matters.
URL / Absolute vs Relative Paths	`a.md` (`href`), `img.md` (`src`), `link.md` (`href`), `script.md` (`src`), `iframe.md` (`src`)	Nearly every HTML element that loads a resource uses a URL, but the concept of a URL and the difference between absolute and relative paths is never taught.
`src` Attribute	`img.md`, `audio.md`, `video.md`, `iframe.md`, `script.md` — all rely on `src`	The `src` attribute appears in 5+ existing term docs as the primary way to load external resources but is never defined as its own term.
Accessibility (a11y) Fundamentals	`semantic_html.md`, `alt.md`, `label.md`, `form.md`, `nav.md`, `main.md`, `header.md`, `footer.md` — all reference "screen readers" and "accessibility"	Almost every Level 5–7 doc assumes the learner knows what accessibility is, what a screen reader does, and why it matters. This umbrella concept is never introduced.

2. Missing Terms by Level

Legend for Category: Structural Tag / Inline Text Semantics / Form Element / Media Element / Metadata / Concept / Architecture / Global Attribute (per _meta/technology_context.md). Prereqs and Related reference existing terms by name (see zero-to-hero list) or other missing terms (marked with 🆕).

Level 1 — The Anatomy of a Webpage (foundational concepts)

#	Proposed Term	One-line description	Category	Prerequisites	Related
1	Block-level vs Inline Elements [DONE]	The two fundamental display behaviors: block takes full width with line breaks; inline flows within text.	Concept / Architecture	Element vs. Tag, `<body>`	`<div>`, `<span>`, `<p>`, 🆕 Void Elements
2	Void Elements (Self-closing Tags) [DONE]	Elements that cannot have children and have no closing tag (e.g., `<br>`, `<img>`, `<input>`, `<meta>`).	Concept / Architecture	Element vs. Tag	`<img>`, `<input>`, `<meta>`, `<link>`, `<br>`
3	Comments (`<!-- -->`) [DONE]	Invisible annotations in the source code for developer notes.	Concept / Architecture	HTML	Nesting, 🆕 Debugging HTML
4	URL (Uniform Resource Locator) [DONE]	The web address system; absolute vs relative paths.	Concept / Architecture	HTML	`<a>`, `href`, `<img>`, 🆕 `src` Attribute

Level 2 — Text & Content (inline formatting gaps)

#	Proposed Term	One-line description	Category	Prerequisites	Related
5	`<b>`, `<i>`, `<u>` vs `<strong>`, `<em>`, `<ins>` [DONE]	The difference between presentational (visual-only) tags and semantic (meaningful) tags.	Inline Text Semantics	`<strong>` & `<em>`, 🆕 Block vs Inline	Semantic HTML, 🆕 Accessibility Fundamentals
6	`<blockquote>` & `<cite>` [DONE]	Semantic tags for quoting external sources and attributing citations.	Inline Text Semantics	`<p>`, Semantic HTML	`<strong>` & `<em>`, 🆕 `<figure>` & `<figcaption>`
7	`<pre>` & `<code>` [DONE]	Tags for displaying preformatted text and inline code snippets, preserving whitespace.	Inline Text Semantics	Whitespace Collapse, `<p>`	`<span>`, 🆕 HTML Entities
8	`<sup>` & `<sub>` [DONE]	Superscript and subscript text (e.g., footnotes, chemical formulas).	Inline Text Semantics	Element vs. Tag, 🆕 Block vs Inline	`<span>`

Level 3 — Media & Embedding (missing resource concepts)

#	Proposed Term	One-line description	Category	Prerequisites	Related
9	`src` Attribute [DONE]	Specifies the URL of an external resource to embed (images, scripts, media).	Global Attribute	Attribute, 🆕 URL	`<img>`, `<audio>`, `<video>`, `<iframe>`, `<script>`
10	`<figure>` & `<figcaption>` [DONE]	Semantic container for self-contained media content (images, diagrams) with an optional caption.	Structural Tag	`<img>`, `alt`, Semantic HTML	`<article>`, 🆕 `<blockquote>`
11	`<source>` Element [DONE]	Specifies multiple media resources for `<audio>`, `<video>`, and `<picture>` for browser compatibility.	Media Element	`<audio>`, `<video>`	`<picture>`, 🆕 Responsive Images
12	`<picture>` & Responsive Images [DONE]	Serve different images for different screen sizes/resolutions using `<picture>` and `srcset`.	Media Element	`<img>`, `alt`, 🆕 `<source>`	🆕 Viewport, `<meta>`

Level 4 — Tables (missing table attributes)

#	Proposed Term	One-line description	Category	Prerequisites	Related
13	`colspan` & `rowspan` [DONE]	Attributes that let a table cell span across multiple columns or rows.	Structural Tag	`<td>`, `<th>`, `<table>`	`<thead>`, `<tbody>`, `<tfoot>`
14	`<caption>` [DONE]	A semantic title/description for a table, crucial for accessibility.	Structural Tag	`<table>`, 🆕 Accessibility Fundamentals	`<th>`, 🆕 scope attribute
15	`scope` Attribute (in `<th>`) [DONE]	Tells screen readers whether a header cell applies to a column, row, or group.	Concept / Architecture	`<th>`, 🆕 Accessibility Fundamentals	🆕 caption attribute, `<thead>`

Level 5 — Forms & User Input (critical form gaps)

#	Proposed Term	One-line description	Category	Prerequisites	Related
16	`placeholder` Attribute [DONE]	A temporary hint displayed inside an input field before the user enters a value.	Global Attribute	`<input>`, `<textarea>`	`value` attribute, `<label>`
17	`value` Attribute (in Form Fields) [DONE]	Defines the current or default text value of an input field, button, or option.	Global Attribute	`<input>`, `<select>` & `<option>`	`placeholder` attribute, `<form>`
18	`name` Attribute (in Form Fields) [DONE]	Assigns a key name to form data sent to a server, critical for grouping radio buttons.	Global Attribute	`<input>`, `<form>`	🆕 `<input type="radio">`, `value` attribute
19	`<input type="radio">` & `<input type="checkbox">` [DONE]	Form controls for selecting single (radio) or multiple (checkbox) options.	Form Input Tag	`<input>`, 🆕 name attribute	`value` attribute, `<label>`
20	`action` & `method` Attributes [DONE]	Attributes that control where form data is sent (action) and how (method: GET/POST).	Global Attribute	`<form>`, 🆕 URL	`<button>`, 🆕 name attribute
21	`<fieldset>` & `<legend>`	A semantic container for grouping related form controls together with a label.	Form Element	`<form>`, `<input>`, `<label>`	Semantic HTML, 🆕 Accessibility Fundamentals
22	`<datalist>`	Provides a list of pre-defined autocomplete options for an `<input>` element.	Form Element	`<input>`, `<select>` & `<option>`	🆕 Form Validation
23	`<output>`	A semantic element for displaying the result of a calculation or user action.	Form Element	`<form>`, `<input>`	`<span>`, `<script>`

Level 6 — Semantic HTML5 (missing semantic tags)

#	Proposed Term	One-line description	Category	Prerequisites	Related
23	`<aside>` [DONE]	Represents content tangentially related to the main content (sidebars, pull quotes, ads).	Structural Tag	Semantic HTML, `<main>`	`<article>`, `<section>`, `<nav>`
24	`<details>` & `<summary>` [DONE]	A native HTML disclosure widget — an interactive element users can expand/collapse without JavaScript.	Structural Tag	Semantic HTML, Element vs. Tag	`<script>`, 🆕 Accessibility Fundamentals
25	`<time>` & `datetime` Attribute [DONE]	A semantic tag for representing dates/times in a machine-readable format.	Inline Text Semantics	Semantic HTML, Attribute	`<article>`, `<meta>`
26	`<address>` [DONE]	Semantic tag for contact information of the nearest `<article>` or `<body>` ancestor.	Structural Tag	Semantic HTML, `<footer>`	`<article>`, `<a>`
27	`<mark>` [DONE]	Semantic tag for highlighted/marked text (e.g., search result highlighting).	Inline Text Semantics	`<strong>` & `<em>`, Semantic HTML	`<span>`, 🆕 `<b>` vs `<strong>`
28	Heading Hierarchy & Document Outline [DONE]	The correct use of `<h1>` through `<h6>` to create a logical, nested document outline for SEO and accessibility.	Concept / Architecture	Headings (`<h1>` to `<h6>`), Semantic HTML	`<section>`, `<article>`, 🆕 Accessibility Fundamentals

Level 7 — Global Attributes & Styling Concepts (missing attributes)

#	Proposed Term	One-line description	Category	Prerequisites	Related
29	`title` Attribute [DONE]	Defines advisory information for an element, typically rendered as a tooltip on hover.	Global Attribute	Attribute	`alt` attribute, `<abbr>`
30	`lang` Attribute [DONE]	Specifies the primary language of the element's text content, crucial for screen readers and translation.	Global Attribute	Attribute, `<html>`	`meta` tag
31	`tabindex` Attribute [DONE]	Controls whether an element can be focused via keyboard navigation and in what order.	Global Attribute	Attribute, 🆕 button	🆕 anchor, 🆕 Accessibility Fundamentals
32	*`data-` Attributes** [DONE]	Allows storing custom metadata on standard HTML elements for scripting and styling.	Global Attribute	Attribute	`class` attribute, `id` attribute, `<script>`
33	`contenteditable` Attribute	Makes any HTML element editable by the user directly in the browser.	Global Attribute	Attribute, DOM	`<textarea>`, `<script>`
34	`hidden` Attribute	A boolean attribute that hides an element from rendering (semantic equivalent of `display: none`).	Global Attribute	Attribute, `style`	`<script>`, DOM, `class`

Level 8 — Metadata, SEO & Head (missing head-level concepts)

#	Proposed Term	One-line description	Category	Prerequisites	Related
35	`<style>` Element [DONE]	An element placed in the `<head>` to define internal CSS rules for the document.	Metadata	`<head>`, `style` attribute, `<link>`	`class`, `id`
36	Favicon [DONE]	The small icon displayed in the browser tab, configured via `<link rel="icon">`.	Metadata	`<link>`, `<head>`	🆕 Open Graph Tags, `<meta>`
37	`<base>` Element [DONE]	Sets the default base URL and target for all relative URLs in the document.	Metadata	`<head>`, 🆕 URL	`<a>`, `href`, `<link>`
38	Character Encoding (`charset`) [DONE]	The system used to translate binary data into human-readable text; `UTF-8` is the modern universal standard.	Concept / Architecture	`<meta>`, `<head>`	🆕 HTML Entities
39	`defer` & `async` (Script Loading Strategies) [DONE]	Two attributes on `<script>` that control when external scripts are downloaded and executed relative to HTML parsing.	Concept / Architecture	`<script>`, `<head>`, DOM	🆕 Render-Blocking, 🆕 Critical Rendering Path
40	`<noscript>` [DONE]	Provides fallback content for users whose browsers have JavaScript disabled.	Structural Tag	`<script>`, `<body>`	🆕 Accessibility Fundamentals
40a	Open Graph Tags (`og:`) [DONE]	Meta tags that control how a webpage appears when shared on social media (Facebook, Twitter, LinkedIn).	Metadata	`<meta>`, `<head>`	🆕 SEO Fundamentals, `<link>`

Level 9 — DOM, Rendering & Accessibility (bridging HTML to JavaScript)

#	Proposed Term	One-line description	Category	Prerequisites	Related
41	Accessibility (a11y) Fundamentals [DONE]	The practice of making web content usable by all people, including those with disabilities; introduces screen readers, keyboard navigation, and WCAG.	Concept / Architecture	Semantic HTML, `alt`, `<label>`	ARIA Attributes, `tabindex`, 🆕 Heading Hierarchy
42	ARIA Attributes [DONE]	Accessible Rich Internet Applications attributes (`role`, `aria-label`, `aria-hidden`, etc.) used when semantic HTML alone is insufficient.	Concept / Architecture	🆕 Accessibility Fundamentals, Semantic HTML, Attribute	`tabindex`, `<nav>`, `<main>`
43	`tabindex` [DONE]	An attribute controlling keyboard focus order, making non-interactive elements focusable or removing focus from interactive ones.	Global Attribute	Attribute, 🆕 Accessibility Fundamentals	ARIA Attributes, `<button>`, `<a>`
44	HTML Entities [DONE]	Special character codes like `&`, `<`, `©`, ` ` used to display reserved or special characters.	Concept / Architecture	HTML, Element vs. Tag	🆕 Character Encoding, `<pre>` & `<code>`
45	SEO Fundamentals for HTML [DONE]	How HTML structure (headings, meta tags, semantic elements, alt text) directly impacts search engine ranking.	Concept / Architecture	`<meta>`, `<title>`, Semantic HTML, Headings	🆕 Open Graph Tags, 🆕 Heading Hierarchy, `alt`
46	Critical Rendering Path [DONE]	How the browser converts HTML, CSS, and JavaScript into visible pixels: parsing → DOM tree → CSSOM → render tree → paint.	Concept / Architecture	DOM, Tree Structure, `<link>`, `<script>`	🆕 `defer` & `async`, 🆕 Render-Blocking
47	Render-Blocking Resources [DONE]	CSS and synchronous JavaScript that prevent the browser from displaying content until they finish loading.	Concept / Architecture	`<link>`, `<script>`, 🆕 Critical Rendering Path	🆕 `defer` & `async`, `<style>` Element

Level 10 — HTML5 APIs & Modern HTML (advanced features)

#	Proposed Term	One-line description	Category	Prerequisites	Related
48	Web Components (`<template>`, `<slot>`, Shadow DOM) [DONE]	A suite of native browser technologies for creating reusable, encapsulated custom HTML elements.	Concept / Architecture	DOM, `<script>`, 🆕 `data-*` Attributes	`<canvas>`, `<svg>`
49	`<dialog>` Element [DONE]	A native HTML element for creating modal and non-modal dialog boxes without JavaScript frameworks.	Structural Tag	DOM, `<button>`, 🆕 Accessibility Fundamentals	🆕 `<details>` & `<summary>`, ARIA Attributes
50	Drag & Drop API [DONE]	HTML5 attributes (`draggable`, `ondragstart`, `ondrop`) enabling native drag-and-drop interactions.	Concept / Architecture	DOM, `<script>`, Attribute	`<canvas>`, 🆕 `data-*` Attributes
51	Geolocation API [DONE]	An HTML5 API that lets web applications access the user's geographic location (with permission).	Concept / Architecture	`<script>`, DOM	Web Storage, 🆕 Permissions & Security
52	`<progress>` & `<meter>` [DONE]	Native HTML5 elements for displaying progress bars and scalar measurements without JavaScript.	Form Element	Element vs. Tag, 🆕 `value` Attribute	`<output>`, `style` attribute
53	Content Security Policy (CSP) & HTML Security [DONE]	How HTML attributes (`sandbox`, `referrerpolicy`, `integrity`) and headers protect against XSS and injection attacks.	Concept / Architecture	`<script>`, `<iframe>`, 🆕 HTML Entities	🆕 `<noscript>`, Web Storage
54	`<map>` & `<area>` (Image Maps) [DONE]	Tags for defining clickable regions within an image, enabling interactive graphics without JavaScript.	Media Element	`<img>`, `href`, Attribute	`<svg>`, `<canvas>`

3. Relationship Map (dependency graph)

How the missing terms connect to each other and to existing terms. A → B means "understanding A meaningfully requires B" (B is a prerequisite of A).

3.1 The "Block vs Inline" chain (unblocks the most understanding)

Element vs. Tag (exists)
   → Block-level vs Inline Elements 🆕  ← THE keystone HTML gap
        → <div> (exists, calls itself "block container")
        → <span> (exists, calls itself "inline container")
        → Void Elements 🆕 → <img>, <input>, <br>, <meta>, <link> (all exist)
        → <b>/<i> vs <strong>/<em> 🆕 (presentational vs semantic inline)

3.2 URL & Resource loading chain

HTML (exists)
   → URL / Absolute vs Relative Paths 🆕
        → href (exists), src 🆕
             → <img> (exists), <audio> (exists), <video> (exists)
             → <iframe> (exists), <script> (exists), <link> (exists)
        → <base> element 🆕

3.3 Forms cluster (the biggest gap area)

<form> (exists) + <input> (exists)
   → name Attribute 🆕 + value Attribute 🆕  ← form data fundamentals
        → action & method (exists)
        → <select> & <option> (exists), <textarea> (exists)
   → required/placeholder/disabled 🆕 → Form Validation (HTML5) 🆕
   → <fieldset> & <legend> 🆕 → Accessibility 🆕
   → <datalist> 🆕, <output> 🆕

3.4 Accessibility & semantic cluster

Semantic HTML (exists) + alt (exists) + <label> (exists)
   → Accessibility (a11y) Fundamentals 🆕  ← umbrella concept
        → ARIA Attributes 🆕 (referenced in zero-to-hero but no file)
        → tabindex 🆕 (referenced in zero-to-hero but no file)
        → <caption> 🆕 + scope 🆕 (table accessibility)
        → Heading Hierarchy 🆕 → SEO Fundamentals 🆕

3.5 Head & metadata cluster

<head> (exists) + <meta> (exists)
   → Character Encoding (charset) 🆕 → HTML Entities 🆕
   → Open Graph Tags 🆕 (mentioned in meta.md exercise but no dedicated term)
   → <style> element 🆕 (vs style attribute, exists)
   → Favicon 🆕
   → <base> 🆕
   → <noscript> 🆕

3.6 Rendering & performance cluster

DOM (exists) + Tree Structure (exists)
   → Critical Rendering Path 🆕
        → Render-Blocking Resources 🆕
             → defer & async 🆕 (on <script>)
             → <link> blocking CSS (exists)

3.7 Semantic text & media cluster

<p> (exists) + <strong>/<em> (exists)
   → <blockquote> & <cite> 🆕
   → <pre> & <code> 🆕
   → <sup> & <sub> 🆕
   → <mark> 🆕
   → <time> 🆕
<img> (exists) + <video> (exists)
   → <figure> & <figcaption> 🆕
   → <source> 🆕 → <picture> & Responsive Images 🆕

3.8 HTML5 advanced cluster

DOM (exists) + <script> (exists)
   → Web Components 🆕 (template/slot/shadow DOM)
   → <dialog> 🆕
   → Drag & Drop API 🆕
   → Geolocation API 🆕
   → <progress> & <meter> 🆕
   → Content Security Policy 🆕

4. Suggested Generation Priority

Ordered so each batch unblocks the next (and repairs the most existing prose references).

Tier	Rationale	Terms
P0 — Repairs pervasive references	Used in existing docs but undefined; blocks basic comprehension	Block-level vs Inline Elements; Void Elements; URL / Absolute vs Relative Paths; `src` Attribute; `name` Attribute; `value` Attribute; Comments (`<!-- -->`); Accessibility (a11y) Fundamentals
P1 — Completes the zero-to-hero list	Listed in `_meta/html_terms_zero_to_hero.md` (#45 `<aside>`, #47 Open Graph, #50 ARIA, #51 tabindex, #52 HTML Entities) but have no term files	`<aside>`; Open Graph Tags; ARIA Attributes; `tabindex`; HTML Entities
P2 — Form completion	The forms level (#5) is the weakest; these make it self-contained	`required`/`placeholder`/`disabled`/`readonly`; Form Validation (HTML5); `<fieldset>` & `<legend>`; `<datalist>`; `<output>`
P3 — Semantic text & media breadth	Essential text/media tags missing from Levels 2–3	`<b>/<i>` vs `<strong>/<em>`; `<blockquote>` & `<cite>`; `<pre>` & `<code>`; `<sup>` & `<sub>`; `<figure>` & `<figcaption>`; `<source>`; `<picture>` & Responsive Images; `<mark>`; `<time>`
P4 — Head, metadata & rendering	Complete the invisible infrastructure of a webpage	Character Encoding; `<style>` Element; Favicon; `<base>`; `defer` & `async`; `<noscript>`; Heading Hierarchy; SEO Fundamentals; Critical Rendering Path; Render-Blocking Resources
P5 — Global attributes	Round out attribute knowledge	`data-*` Custom Attributes; `hidden` Attribute; `title` Attribute; `lang` Attribute; `contenteditable`; `colspan` & `rowspan`; `<caption>`; `scope` Attribute
P6 — HTML5 & modern features	Advanced features for experienced learners	`<details>` & `<summary>`; `<address>`; `<dialog>`; Web Components; `<progress>` & `<meter>`; Drag & Drop API; Geolocation API; Content Security Policy; `<map>` & `<area>`

5. Notes for the Generating AI

Follow the existing template. Every new file must mirror the 8-section structure used in terms/level_XX/*.md (Prerequisites → Term Category → Environment Context → Explanation [Design Motivation / Reality Metaphor / Code Examples] → Common Mistakes → Practice Exercises → Related Terms → Key Takeaways) and obey _meta/technology_context.md (W3C Web Standards Author & Accessibility Advocate persona; lowercase tags; double-quoted attributes; include alt on <img>; use semantic tags; <label> for all <input>s; 2-space indentation).
Wire the cross-links. Use the Prerequisites and Related columns in Section 2 to populate ## 1. Prerequisites and ## 7. Related Terms with correct relative paths (../level_XX/<term>.md). When a new term links to another new term, create both.
Renumber intentionally. The zero-to-hero list ends at #52; either append new numbers or switch to level-relative numbering — decide once and stay consistent.
Update the trackers. After generating, add each new term to _meta/html_terms_zero_to_hero.md and remove it from this gap list (or mark it done), mirroring how _meta/missing_terms.md records already-closed gaps.
Environment tags. Most HTML terms = Universal Browser Support; HTML5-specific features (like <dialog>, <details>, Web Components) = Modern Browsers (HTML5); concepts that involve JavaScript APIs (like Geolocation, Drag & Drop) = HTML5 Standard.
Tone for absolute beginners. Remember the audience is someone who has never coded before. Use the W3C persona from technology_context.md but keep explanations simple, jargon-free, and full of real-world metaphors.
<aside> already exists in zero-to-hero list (#45) but has NO file. Generate it as part of the P1 batch along with other listed-but-unwritten terms.