Rich Marker Descriptions

A marker description can be more than a paragraph of text. Write a small set of HTML tags in the description box and the marker’s popup renders them: headings, bold and italic, inline code, lists, links, tables, and an embedded line chart.

Plain text still works exactly as before — if you don’t use any tags, nothing changes.

Formatting, lists, and links

That popup came from this description:

<h2>Site notes</h2>
Readings look <b>stable</b>, but sensor <code>A1</code> is <i>drifting</i>.
<ul><li>Recalibrate on Tuesday</li><li>Replace the battery</li></ul>
<a href="https://www.swisstopo.admin.ch">Reference station data</a>

Tags you can use

Purpose	Tags
Emphasis	<b> <strong> <i> <em> <u>
Code	<code>
Headings	<h1> <h2> <h3>
Lists	<ul> <ol> <li>
Paragraphs & breaks	<p> <br> <hr>
Links	<a href="https://…">
Tables	<table> <tr> <th> <td> (<thead>/<tbody> optional)
Charts	<chart> — see below

Blank lines start a new paragraph and single line breaks are kept, so you can write ordinary text and reach for a tag only where you need one.

Note

Anything outside that list is simply ignored — the tag disappears and its text stays. Links must start with http:// or https://; other kinds of link are shown as plain text.

Add a table

<h3>Water level by station</h3>
<table>
<tr><th>Station</th><th>Level</th><th>Trend</th></tr>
<tr><td>A1</td><td>2.4 m</td><td>rising</td></tr>
<tr><td>B7</td><td>1.9 m</td><td>steady</td></tr>
<tr><td>C3</td><td>3.1 m</td><td>falling</td></tr>
</table>

A first row made entirely of <th> cells becomes the header. You don’t need <thead> or <tbody> — they’re added for you. A marker with a table gets a wider popup, and a very wide table scrolls sideways inside it.

Table text is searchable: the Markers panel finds a marker by a value that appears only inside a cell.

Add a line chart

Put a <chart> tag in the description with its data as JSON inside.

<chart>{
  "v": 1,
  "type": "line",
  "title": "Water level",
  "xLabel": "week",
  "yLabel": "m",
  "series": [
    { "label": "A1", "points": [[1, 2.1], [2, 2.4], [3, 2.2], [4, 2.9]] },
    { "label": "B7", "points": [[1, 3.4], [2, 3.1], [3, 3.6], [4, 3.2]] }
  ]
}</chart>

Each entry in series is one line. points is a list of [x, y] pairs — they don’t need to be in order. title, xLabel, yLabel, and each series label are optional; a label is worth adding when you have more than one line, because it names the line in the legend.

Field	Notes
v	Always 1.
type	Always "line".
series	1–4 series, up to 1,000 points in total.
label	Series name, shown in the legend.
color	Optional hex colour, e.g. "#315ee7". Leave it out to use the built-in palette.

Each line gets its own colour and its own dash pattern, so the lines stay tellable apart when printed in black and white or read by someone with colour-vision deficiency.

Caution

If the JSON has a typo, the popup shows a small “Chart data could not be read.” note instead of the chart — the rest of your description still renders normally.

Preview while you write

Authoring a table or a chart’s JSON blind is no fun, so the description box has a Preview toggle. It renders exactly what the popup will show.

1. Type your description in the Add Marker or Edit Marker panel.

2. Click Preview above the box.

3. The rendered result appears underneath. Keep editing — it updates as you type.

Good to know

• Everywhere else shows plain text. The markers list, presentation callouts, the history view, and exported files show a readable text version of your description. Only the map popup renders the formatting.
• Descriptions are shared. Everyone in the room — and anyone viewing a public room — sees what you write, so it renders the same for them as it does for you.
• There’s a size limit. A description can be up to 20,000 characters. The box tells you when you’re close, and a description past the limit falls back to plain text.
• Exports keep your formatting. Export a room and re-import it and the rich description comes back exactly as written.

Markers & DrawingPlacing markers, icons, photos, dates, and drawn shapes.