# Frequently Asked Questions (FAQ)

## Which syntax is allowed in description fields? {: #text-formatting }

* `*single star for italic*` → *single star for italic*
* `**double star for bold**` → **double star for bold**
* `# one hash for main heading` ⤵ <h1>one hash for main heading</h1>
* `## two hashes for second heading` ⤵ <h2>two hashes for second heading</h2>
* `### three hashes for third heading` ⤵ <h3>three hashes for third heading</h3>
* `Simple link: [[http://example.com]]` → Simple link: [http://example.com](http://example.com)
* `Link with text: [[http://example.com|text of the link]]` → Link with text: [text of the link](http://example.com)
* `--- for a horizontal rule` ⤵ <hr>

## What are the available keyboard shortcuts? {: #keyboard-shortcuts}

With macOS, replace `Ctrl` by `Cmd`.

### Globals

* `Ctrl+F` → open search panel
* `Ctrl+E` → switch to edit mode
* `Escape` → close open panel or dialog
* `Shift+drag` on the map → zoom to this map extent
* `Shift+click` on the zoom buttons → zoom in/out by 3 levels

### In edit mode

* `Ctrl+E` → back to preview mode
* `Ctrl+S` → save map
* `Ctrl+Z` → undo all changes until last save
* `Ctrl+M` → add a new marker
* `Ctrl+P` → start a new polygon
* `Ctrl+L` → start a new line
* `Ctrl+I` → open importer panel
* `Ctrl+O` → open importer panel and file browser
* `Ctrl++` → zoom in
* `Ctrl+-` → zoom out
* `Shift+click` on a feature → edit this feature
* `Ctrl+Shift+click` on a feature → edit this feature layer

## Which syntax is allowed in conditional rules? {: #conditional-rules }

* `mycolumn=odd` → will match features whose column `mycolumn` equal `odd`
* `mycolumn!=odd` → will match features whose column `mycolumn` is missing or different from `odd`
* `mycolumn>12` → will match features whose column `mycolumn` is greater than `12` (as number)
* `mycolumn<12.34` → will match features whose column `mycolumn` is lower than `12.34` (as number)
* `mycolumn=` → will match features whose column `mycolumn` has no or null value
* `mycolumn!=` → will match features whose column `mycolumn` has any defined
* `mycolumn=true/false` → will match features whose column `mycolumn` is explicitely `true` (or `false`)
* `mycolumn!=true/false` → will match features whose column `mycolumn` is different from `true` (or `false`)

When the condition match, the associated style will be applied to the corresponding feature.


## How to use variables ? {: #variables}

In general, using a variable is as simple as `{myvar}`.

It's possible to define another variable as fallback of the first one like this: `{myvar|fallbackvar}`.

To fallback to a string, add it between double quotes: `{myvar|"fallback"}`.

It's possible to combine more variables: `{myvar|othervar|"some string"}`.

It's possible to use a variable inside an URL, for example: `[[https://domain.org/?locale={locale}|Wikipedia]]`.

Or even as source for an image: `{{{myvar}}}` (note the triple `{}`).

### Available variables for features:

Those variables can be used in a feature description, or in popup content templates.

Any property of the feature will be available, plus:

- `{lat}/{lng}` → the feature position (or centroid in case of line or polygon)
- `{alt}` → the altitude of a marker, if defined in the data
- `{locale}` → the locale in the form `en` or `en_US` when a variant is used
- `{lang}` → the lang in the form `en` or `en-us` when a variant is used
- `{measure}` → the length of a line or the area of a polygon
- `{gain}`/`{loss}` → the elevation gain/loss of a line (only if it contains the altitude information)
- `{rank}` → the rank of the feature in the layer
- `{layer}` → the name of the feature's layer
- `{zoom}` → the current map zoom

### Available variables in URL for remote data:

- `{bbox}` → the current bbox of the map in the form `southwest_lng,southwest_lat,northeast_lng,northeast_lat`
- `{north}/{top}` → the North latitude of the current map view
- `{south}/{bottom}` → the South latitude of the current map view
- `{east}/{right}` → the East longitude of the current map view
- `{west}/{left}` → the West longitude of the current map view
- `{zoom}` → the current map zoom
- `{lat}` → the latitude of the current map center
- `{lng}` → the longitude of the current map center