JTOO is a structured human-readable data format. It is an alternative to JSON.

Author: Michael Leonhard https://tamale.net/

• Human readable
• Well-defined data types matching the data types in most modern programming languages
• Compact
• Quickly parsed by machine

application/jtoo

• A JTOO document is a single instance of a JTOO data type, encoded in UTF-8.
• Example: ["msg":"你好"] encodes as bytes 5b 22 6d 73 67 22 3a 22 e4 bd a0 e5 a5 bd 22 5d

• A string is a sequence of zero or more Unicode codepoints (characters).
• Examples:
  • ""
  • "abc"
  • "She typed \22ok\22."
  • "C:\5cWindows
• Parsers MUST accept these codepoints escaped in lower-case hex format:
  • Control codes: \00, \01, \02, \03, \04, \05, \06, \07, \08, \09 tab, \0a line feed, \0b, \0c, \0d carriage return, \0e, \0f, \10, \11, \12, \13, \14, \15, \16, \17, \18, \19, \1a, \1b, \1c, \1d, \1e, \1f, \7f
  • Double-quote: \22
  • Backslash: \5c
• Parsers MUST reject strings with these codepoints un-escaped or with other escaped codepoints. This helps prevent request smuggling attacks.

• A byte string is a sequence of zero or more bytes, prefixed with B.
• Each byte is encoded in lower-case hexadecimal format.
• Examples:
  • B ("")
  • B61 ("a")
  • B4f4b ("OK")
• Parsers must reject byte strings with whitespace: B 4f, B4f 4b.

Y or N

• Base-10
• Groups of three digits must be separated from the rest of the number with _, starting from the least-significant digits.
• Examples:
  • 0
  • 1
  • -1
  • 1_000
• Parsers MUST reject integers with unnecessary leading zeros: 00, 000, etc.

• Decimals are numbers with a fractional part.
• Examples:
  • 0.0
  • 1.0
  • -1.0
  • 1_000.0
  • 0.000_1
• Groups of three digits must be separated from the rest of the number with _, starting from the decimal point.
• Parsers MUST reject decimal numbers with unnecessary leading zeros: 00.0, 01.0, etc.

Use ISO-8601 to interpret dates and times. Note that JTOO allows only one format for each kind of value.

Date values:

• year: D2023
• month: D2023-01
• week: D2023-W01
• date: D2023-01-01

Time values:

• hour: T01 (00-23)
• minute: T23:01 (00-59)
• second: T01:02:03 (0-60)
• millisecond: T01:02:03.004 (000-999)
• microsecond: T01:02:03.004_005 (000_000-999_999)
• nanosecond: T01:02:03.004_005_006 (000_000_000-999_999_999)

Timezone values:

• Z (UTC)
• Hour offset: -08 (Pacific Standard Time)
• Hour and minute offset: +0530 (Indian Standard Time)
• Parsers MUST reject timezone values with 00 minute part. Example: +0800

Combinations of date + timezone, time + timezone, and date + time + timezone. Examples:

• year-timezone: D2023Z
• date-hour: concatenate a date and hour, D2023-12-30T01
• date-minute: concatenate a date and minute: D2023-12-30T01:02
• date-second-timezone: concatenate a date and second: D2023-12-30T01:02:03-08

Timestamp values:

• timestamp-second: seconds since the epoch, S0 (the unix epoch, 1980-01-01:00:00:00Z), S1_709_528_240
• timestamp-millisecondS1_709_528_240.001
• timestamp-microsecond: S1_709_528_240.000_001
• timestamp-nanosecond: S1_709_528_240.000_000_001

• [, then a sequence of zero or more values of any type, separated by ,, then ].
• Examples:
  • []
  • [1,2,3,4]
  • [t,f]
  • [[1,2],[3,4]]

JTOO libraries may include separate functions for parsing a related format called HTOO, a less-strict Human-writable variant of JTOO.

MIME Type: application/htoo

An HTOO parser MUST behave like a JTOO parser and also MUST:

• Allow end-of-line comments: 1 // This is a comment.
• Allow interior non-nesting comments: ["a" /* This is a comment. */,"b"].
• Allow trailing commas
  • [1,]
  • [[1,2,],]
• Allow whitespace between elements
  • [1 ]
  • [1, 2]
  • [["a", 1], ["b", 2]]

  • [
      ["a", 1],
      ["b", 2],
    ]
    

• Allow these non-standard character escapes: \t, \r, \n, \"
• Allow byte strings to contain upper-case hexadecimal digits.
• Allow decimal numbers with unnecessary trailing zeros: 0.00
• Allow numbers without _ separators.
• Allow numbers with _ separators between any two digits.
• Allow timezones with 00 minute part: -0800, +0500.

• Thanks to Emma Wang for suggesting the name, "J-two".
• Thanks to the authors of other interchange formats for their development and documentation:
  • JSON https://www.json.org/
  • Amazon Ion https://amazon-ion.github.io/ion-docs/docs.html
  • Protocol Buffers https://protobuf.dev/