Whitespace & Indentation

Recognized whitespace characters and how the parser treats them.

In the Internet Object format, whitespace is any character with a Unicode code point less than or equal to U+0020 (the range U+0000 to U+0020). This range covers both non-printable control characters and common whitespace 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).

Because the format is not whitespace-sensitive, indentation carries no meaning: it is ordinary whitespace between tokens. You may indent objects, arrays, and definitions freely for readability without changing how a document parses.

EBNF definition

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 ;

Beyond the U+0000–U+0020 range, the format also treats characters in the Unicode whitespace category as whitespace, such as the non-breaking space (U+00A0), em space (U+2003), and en space (U+2002). Recognizing these makes the format easier to work with in languages that use non-Latin scripts, such as Arabic, Chinese, or Japanese.

The format also 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, etc.	Any character with code point <= 0x20. Includes the ASCII space and control characters.
U+1680	Ogham space mark	Space used in Ogham script.
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.
U+2008	Punctuation space	Space used for punctuation.
U+2009	Thin space	Space narrower than the regular space.
U+200A	Hair space	Very narrow space used for special purposes.
U+2028	Line separator	Separates lines of text.
U+2029	Paragraph separator	Separates paragraphs of text.
U+202F	Narrow no-break space	Non-breaking space narrower than the regular space.
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 — the parser ignores whitespace surrounding values and structural elements.

• Preserved inside strings — whitespace within a value or string is kept exactly as written.

• Recognized by code point — whitespace is identified by Unicode code point, per the table above.

• Reserved — these whitespace characters MUST NOT appear within identifiers or keys.

Best practices

• Aid readability — use spaces and tabs to format a document so it is easy to read.

• Avoid clutter — excessive whitespace adds no meaning and reduces readability.

• Stay consistent — apply whitespace uniformly across a document for easier maintenance.

• Watch for invisible characters — zero-width and other invisible spaces can slip into keys or values unnoticed; avoid pasting them in.

See Also

• Encoding — Unicode handling and document encoding

• Strings — whitespace handling inside strings