What are some common placeholder notation recommendations for PHP templates?

When working with PHP templates, it is common to use placeholder notation to dynamically insert content into the template. Some common recommendations for placeholder notation include using curly braces { } or double curly braces {{ }} to surround the placeholder variable. This helps to clearly distinguish the placeholder from surrounding text and makes it easier to identify and replace the placeholders in the template.

// Example of using curly braces for placeholder notation
echo "Hello, {name}!";
```

```php
// Example of using double curly braces for placeholder notation
echo "Hello, {{name}}!";