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N-Triples is a line-based, plain text format for encoding an RDF graph.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.N-Triples was originally defined as a syntax for the RDF Test Cases [RDF-TESTCASES] document. Due to its populatity as exchange format the RDF Working Group decided to publish an updated version. This document is intended to become a Working Group Note.
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Publication as a Working Group Note does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
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This document defines an easy to parse line-based subset of Turtle [TURTLE-TR] named N-Triples.
The syntax is a revised version of N-Triples as originally defined in the RDF Test Cases [RDF-TESTCASES] document. Its original intent was for writing test cases, but it has proven to be popular as a exchange format for RDF data.
An N-Triples document contains no parsing directives.
N-Triples triples are a sequence of RDF terms representing the subject, predicate and object of an RDF Triple. These may be seperated by white space (spaces
#x20 or tabs
#x9). This sequence is terminated by a '
.' and a new line (optional at the end of a document).
N-Triples triples are also Turtle simple triples, but Turtle includes other representations of RDF terms and abbreviations of RDF Triples. When parsed by a Turtle parser, data in the N-Triples format will produce exactly the same triples as a parser for the restricted N-triples language.
The RDF graph represented by an N-Triples document contains
exactly each triple matching the N-Triples
The simplest triple statement is a sequence of (subject, predicate, object) terms, separated by whitespace and terminated by '
.' after each triple.
IRIs may be written only as absolute IRIs.
IRIs are enclosed in '<' and '>' and may contain numeric escape sequences (described below). For example
Literals are used to identify values such as strings, numbers, dates.
Literals (Grammar production Literal) have a lexical form followed by a language tag, a datatype IRI, or neither.
The representation of the lexical form consists of an
" (U+0022), a sequence of permitted
characters or numeric escape sequence or string escape sequence, and a final delimiter. Literals may not contain the characters
CR. In addition '
\' (U+005C) may not appear in any quoted literal except as part of an escape sequence.
The corresponding RDF lexical form is the characters between the delimiters, after processing any escape sequences.
If present, the language tag is preceded by a '
If there is no language tag, there may be a datatype IRI, preceeded by '
^^' (U+005E U+005E). If there is no datatype IRI and no language tag, the datatype is
Include examples with a few escapes for new lines, etc
RDF blank nodes in N-Triples are expressed as
_: followed by a blank node label which is a series of name characters.
The characters in the label are built upon PN_CHARS_BASE, liberalized as follows:
_and digits may appear anywhere in a blank node label.
.may appear anywhere except the first or last character.
U+2040are permitted anywhere except the first character.
A fresh RDF blank node is allocated for each unique blank node label in a document. Repeated use of the same blank node label identifies the same RDF blank node.
This section is non-normative.
\ffor backspace and form feed
As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.
The key words MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this specification are to be interpreted as described in [RFC2119].
This specification defines conformance criteria for:
A conforming N-Triple document is a Unicode string that conforms to the grammar and additional constraints defined in section 5. Grammar, starting with the
ntriplesDoc production. A N-Triple document serializes an RDF graph.
A conforming N-Triple parser is a system capable of reading N-Triple documents on behalf of an application. It makes the serialized RDF graph, as defined in section 6. Parsing, available to the application, usually through some form of API.
N-Triple seralizers are not defined here, will likely include optional behavior to conform to RDF Test Cases syntax as well.
The IRI that identifies the N-Triple language is:
The media type of N-Triples is
The content encoding of N-Triples is always UTF-8.
See N-Triples Media Type for the media type
N-Triples has been historically provided with other media types. N-Triples may also be provided as
text/plain. When used in this way N-Triples MUST use the escaped form of any character outside US-ASCII. As N-Triples is a subset of Turtle a N-Triples document MAY also be provided as
text/turtle. In both of these cases the document is not an N-Triples document as an N-Triples document is only provided as
A N-Triples document is a Unicode [UNICODE] character string encoded in UTF-8. Unicode codepoints only in the range U+0 to U+10FFFF inclusive are allowed.
The EBNF used here is defined in XML 1.0 [EBNF-NOTATION].
Escape sequence rules are the same as Turtle
[TURTLE-TR]. However, as only the
STRING_LITERAL_QUOTE production is allowed new lines in literals MUST be escaped.
||::=||triple? (EOL triple)
Productions for terminals
It may be simple, but should still be defined.
This section is non-normative.
This section is non-normative.
N-Triples only allows for simple triple statements which MUST NOT contain new lines. A single triple is always a single line of the document.
|single-quoted single-line lexical representation||yes||no||
|double-quoted single-line lexical representation||yes||yes||
|single-quoted multi-line lexical representation||yes||no||
|double-quoted multi-line lexical representation||yes||no||
|labeled blank node||yes||yes||
|blank node property list||yes||no||
The Internet Media Type / MIME Type for N-Triples is "application/n-triples".
It is recommended that N-Triples files have the extension ".nt" (all lowercase) on all platforms.
It is recommended that N-Triples files stored on Macintosh HFS file systems be given a file type of "TEXT".
This information that follows will be submitted to the IESG for review, approval, and registration with IANA.