# Options
Options are special configuration parameters that can be set either in the configuration file under the `options` key,
or in a presentation's front matter under the same key. This last one allows you to customize a single presentation so
that it acts in a particular way. This can also be useful if you'd like to share the source files for your presentation
with other people.
The supported configuration options are currently the following:
## implicit_slide_ends
This option removes the need to use `<!-- end_slide -->` in between slides and instead assumes that if you use a slide
title, then you're implying that the previous slide ended. For example, the following presentation:
```markdown
---
options:
implicit_slide_ends: true
---
Tasty vegetables
================
* Potato
Awful vegetables
================
* Lettuce
```
Is equivalent to this "vanilla" one that doesn't use implicit slide ends.
```markdown
Tasty vegetables
================
* Potato
<!-- end_slide -->
Awful vegetables
================
* Lettuce
```
## end_slide_shorthand
This option allows using thematic breaks (`---`) as a delimiter between slides. When enabling this option, you can still
use `<!-- end_slide -->` but any thematic break will also be considered a slide terminator.
```
---
options:
end_slide_shorthand: true
---
this is a slide
---------------------
this is another slide
```
## h1_slide_titles
This options allows setting whether the first `h1` heading in a slide will automatically become the slide title:
```
---
options:
h1_slide_titles: true
---
# title
# not the first, so no title
```
## command_prefix
Because _presenterm_ uses HTML comments to represent commands, it is necessary to make some assumptions on _what_ is a
command and what isn't. The current heuristic is:
* If an HTML comment is laid out on a single line, it is assumed to be a command. This means if you want to use a real
HTML comment like `<!-- remember to say "potato" here -->`, this will raise an error.
* If an HTML comment is multi-line, then it is assumed to be a comment and it can have anything inside it. This means
you can't have a multi-line comment that contains a command like `pause` inside.
Depending on how you use HTML comments personally, this may be limiting to you: you cannot use any single line comments
that are not commands. To get around this, the `command_prefix` option lets you configure a prefix that must be set in
all commands for them to be configured as such. Any single line comment that doesn't start with this prefix will not be
considered a command.
For example:
```
---
options:
command_prefix: "cmd:"
---
Tasty vegetables
================
* Potato
**That's it!**
```
In the example above, the first comment is ignored because it doesn't start with "cmd:" and the second one is processed
because it does.
## incremental_lists
If you'd like all bullet points in all lists to show up with pauses in between you can enable the `incremental_lists`
option:
```
---
options:
incremental_lists: true
---
* pauses
* in
* between
```
Keep in mind if you only want specific bullet points to show up with pauses in between, you can use the
[`incremental_lists` comment command](../features/commands.md#incremental-lists).
## strict_front_matter_parsing
This option tells _presenterm_ you don't care about extra parameters in presentation's front matter. This can be useful
if you're trying to load a presentation made for another tool. The following presentation would only be successfully
loaded if you set `strict_front_matter_parsing` to `false` in your configuration file:
```markdown
---
potato: 42
---
# Hi
```
## image_attributes_prefix
The [image size](../features/images.md#image-size) prefix (by default `image:`) can be configured to be anything you
would want in case you don't like the default one. For example, if you'd like to set the image size by simply doing
`` you would need to set:
```yaml
---
options:
image_attributes_prefix: ""
---
```
## auto_render_languages
This option allows indicating a list of languages for which the `+render` attribute can be omitted in their code
snippets and will be implicitly considered to be set. This can be used for languages like `mermaid` so that graphs are
always automatically rendered without the need to specify `+render` everywhere.
```yaml
---
options:
auto_render_languages:
- mermaid
---
```
## list_item_newlines
The option allows configuring the number of newlines in between list items, the default being `1`. This cam also be set
via the `list_item_newlines` comment command.
```yaml
---
options:
list_item_newlines: 2
---
```