# Whitespaces

In the Internet Object format, whitespace refers to any character with a Unicode code point less than or equal to `U+0020` (i.e., characters in the range `U+0000` to `U+0020`). This range includes both non-printable control characters and common whitespace characters such as the horizontal tab (`U+0009`), newline (`U+000A`), vertical tab (`U+000B`), form feed (`U+000C`), carriage return (`U+000D`), and space (`U+0020`).

## EBNF Definition

```ebnf
whitespace         = ascii_whitespace | unicode_whitespace ;

ascii_whitespace   = ? any character with Unicode code point U+0000 to U+0020 ? ;
unicode_whitespace = U+1680 | U+2000 | U+2001 | U+2002 | U+2003 | U+2004
                   | U+2005 | U+2006 | U+2007 | U+2008 | U+2009 | U+200A
                   | U+2028 | U+2029 | U+202F | U+205F | U+3000 | U+FEFF ;
```

In addition to the characters in the range `U+0000` to `U+0020`, the Internet Object format also includes characters in the Unicode whitespace category as whitespace. This includes characters such as the non-breaking space (`U+00A0`), em space (`U+2003`), and en space (`U+2002`), among others. Including Unicode whitespace characters can make it easier to work with text in languages that use non-Latin scripts, such as Arabic, Chinese, or Japanese.

It's also worth noting that the Internet Object format recognizes the zero-width non-breaking space (`U+FEFF`) as whitespace. This character is often used as a byte order mark (BOM) in Unicode-encoded documents.

## Whitespace Characters

The following table lists the valid whitespace characters:

| Code Points          | Description                                        | Notes                                                                                              |
| -------------------- | -------------------------------------------------- | -------------------------------------------------------------------------------------------------- |
| `U+0000` to `U+0020` | Space, Line Feed, Carriage Return, Tab, Bell, etc. | Any character having charCode `<=0x20` such as space. Includes ASCII space and control characters. |
| `U+1680`             | Ogham Space Mark                                   | Space used in Ogham scripts.                                                                       |
| `U+2000`             | En Quad                                            | Space equal to the width of the lowercase letter "n".                                              |
| `U+2001`             | Em Quad                                            | Space equal to the width of the uppercase letter "M".                                              |
| `U+2002`             | En Space                                           | Space equal to half the width of the em space.                                                     |
| `U+2003`             | Em Space                                           | Space equal to the width of the em space.                                                          |
| `U+2004`             | Three-per-Em Space                                 | Space equal to one-third of an em space.                                                           |
| `U+2005`             | Four-per-Em Space                                  | Space equal to one-quarter of an em space.                                                         |
| `U+2006`             | Six-per-Em Space                                   | Space equal to one-sixth of an em space.                                                           |
| `U+2007`             | Figure Space                                       | Space equal to the width of a numeral character.                                                   |
| `U+2008`             | Punctuation Space                                  | Space used for punctuation.                                                                        |
| `U+2009`             | Thin Space                                         | Space narrower than the regular space character.                                                   |
| `U+200A`             | Hair Space                                         | Very narrow space used for special purposes.                                                       |
| `U+2028`             | Line Separator                                     | Character used to separate lines in text.                                                          |
| `U+2029`             | Paragraph Separator                                | Character used to separate paragraphs in text.                                                     |
| `U+202F`             | Narrow No-Break Space                              | Non-breaking space narrower than the regular space character.                                      |
| `U+205F`             | Medium Mathematical Space                          | Space used in mathematical notation.                                                               |
| `U+3000`             | Ideographic Space                                  | Space used in East Asian scripts.                                                                  |
| `U+FEFF`             | Byte Order Mark (BOM)                              | Zero Width Non-Breaking Space, often used as a BOM.                                                |

## Rules

* **Whitespace Insensitive**: Internet Object is not whitespace sensitive, meaning that the parser ignores the whitespaces surrounding the values and structural elements
* **String Preservation**: Any whitespace characters found within the values or strings themselves are preserved
* **Unicode Code Points**: All whitespace characters are recognized based on their Unicode code points
* **Reserved Characters**: All listed whitespace characters are reserved and should not be used as part of identifiers or keys

## Best Practices

* **Enhance Readability**: Use whitespace characters like spaces and tabs to format your document for better readability
* **Avoid Unnecessary Whitespace**: While whitespace can improve readability, excessive or unnecessary whitespace can clutter the document
* **Consistent Formatting**: Maintain a consistent use of whitespace throughout the document to ensure uniformity and ease of maintenance
* **Be Mindful of Invisible Characters**: Some whitespace characters, like zero-width spaces, are invisible but can affect the parsing and rendering of the document

## See Also

* [**Encoding**](https://docs.internetobject.org/the-structure/encoding) - Unicode character handling and encoding
* [**String Values**](https://docs.internetobject.org/the-structure/values/string) - Whitespace handling in strings