A table of every HTML element and some properties relevant to formatting HTML into plaintext

plaintextify_html_elements_table.txt

> A table of every HTML element and some properties relevant to formatting
> HTML into plaintext.
>
> Key:
>   transparent
>     elements that are noted in the HTML spec as having a "transparent content model",
>     and aren't [replaced elements]
>       https://developer.mozilla.org/en-US/docs/Web/CSS/Replaced_element
>     (just <a>, <del>, <ins>, and <map>)
>   trans-space
>     elements with transparent content model and *are* replaced elements; will want
>     to plaintext-ify as inline containers but with spaces around contents
>   block
>     noted in the HTML spec for breaking <p> elements, and non-void (only <hr>)
>       https://html.spec.whatwg.org/multipage/syntax.html#optional-tags:the-p-element
>   block-void
>     breaks <p> elements and *is* void (only <hr>)
>   block*
>     not noted in the HTML spec for breaking <p> elements, but for our purposes
>     we want to break lines when we encounter it. Primarily table rows (<tr>s),
>     table row groupings (<thead> <tbody> <tfoot>), and list items (<li>s),
>     because we want each table row or list item to plaintext-ify to its own line.
>     (Table row groupings should only ever be immediately between a <table> and <tr>
>     but just in case I guess.) <dialog> also falls under this but that appears to be
>     a spec bug, bc observed behavior in browsers is it does break <p>s
>       https://github.com/whatwg/html/issues/10590
>   block-void*
>     <br>, which is considered inline-level (aka phrasing content category) by the
>     browser when parsing HTML and does not break paragraphs, but for our purposes
>     we do want to break lines when we encouter it
>   inline
>     noted in the HTML spec for as being in the "phrasing content category" and
>     not noted for having a transparent content model; and neither void nor
>     a replaced element. For our purposes, ends up treated the same as transparent
>   inline-space
>     same as inline, but *is* a replaced element (and non-void). Ends up treated
>     same as trans-space
>   inline-void
>     same as inline, but void meaning empty content model or, for the purposes
>     of plaintext-ifying, we want to ignore its contents (<template>, <slot>,
>     <math>, <svg>)
>   void
>     not in the flow content category in the HTML spec, but void so we want to
>     ignore its contents regardless

> Note: all "flow content" elements that aren't phrasing content and aren't transparent content model, except for <dialog>, breaks paragraphs

transparent     <a>
inline          <abbr>
block           <address>
inline-void     <area>, if it is a descendant of a <map> element
block           <article>
block           <aside>
trans-space     <audio>
inline          <b>
void            <base>
inline          <bdi>
inline          <bdo>
block           <blockquote>
block-void*     <br>
inline-space    <button>
trans-space     <canvas>
inline          <cite>
inline          <code>
void            <col>
void            <colgroup>
inline          <data>
inline          <datalist>
transparent     <del>
block           <details>
inline          <dfn>
block*          <dialog>
block           <div>
block           <dl>
inline          <em>
inline-void     <embed>
block           <fieldset>
block           <figcaption>
block           <figure>
block           <footer>
block           <form>
block           <h1>-<h6>
block           <header>
block           <hgroup>
block-void      <hr>
inline          <i>
inline-void     <iframe>
inline-void     <img>
inline-void     <input>
transparent     <ins>
inline          <kbd>
inline          <label>
block*          <li>
inline-void     <link>, if the itemprop attribute is present
block           <main>
transparent     <map>
inline          <mark>
inline-void     <math>
block           <menu>
inline-void     <meta>, if the itemprop attribute is present
inline-space    <meter>
block           <nav>
inline-void     <noscript>
trans-space     <object>
block           <ol>
inline          <output>
void            <optgroup>
void            <option>
block           <p>
inline-void     <picture>
block           <pre>
inline-space    <progress>
inline-space    <q>
inline-space    <ruby>
inline          <s>
inline          <samp>
inline-void     <script>
block           <search>
block           <section>
inline-void     <select>
void            <source>
inline-void     <slot>
inline          <small>
inline          <span>
inline          <strong>
void            <style>
inline          <sub>
inline          <sup>
inline-void     <svg>
block           <table>
block*          <thead>
block*          <tbody>
block*          <tfoot>
block*          <tr>
inline-space    <th>
inline-space    <td>
inline-void     <template>
inline-void     <textarea>
inline          <time>
void            <title>
void            <track>
inline          <u>
block           <ul>
inline          <var>
trans-space     <video>
inline-void     <wbr>