. Avoid or inside table headers.
* * *
### Use Functions
You can use functions to perform calculations, comparisons, formatting, and logical checks directly inside your PDF template.
The syntax for functions is:
```html
${`FUNCTION_NAME(arguments)`}
```
The supported function types are:
* [Mathematical Functions](/ca/books/help/settings/functions-library.html#mathematical-functions)
* [Text Functions](/ca/books/help/settings/functions-library.html#text-functions)
* [Logical Functions](/ca/books/help/settings/functions-library.html#logical-functions)
Learn more about the [functions library](/ca/books/help/settings/functions-library.html).
Click **Save** in the top right corner after you’ve customized the PDF template.
You can also [edit](/ca/books/help/settings/templates.html#customise-pdf-template), [mark as default](/ca/books/help/settings/templates.html#default-template), [clone](/ca/books/help/settings/templates.html#clone-template), and [delete](/ca/books/help/settings/templates.html#delete-template) the template you created.