UNL document
UNL documents are documents written in UNL. They are plain text files that include UNL Sentences and some special tags. They are the output of the UNLization process and the input of the NLization process.
Syntax
A UNL document is enclosed with tags “[D:<id>]” and “[/D]”. Within these tags, each paragraph is enclosed with a pair of tags “[P:<id>]” and “[/P]”, and each sentence is enclosed with a pair of tags “[S:<id>]” and “[/S]”. Inside a sentence, the text of original sentence is enclosed with “{org:<lang>}” and “{/org}”, its UNL expression is enclosed with “{unl:<id>}” and “{/unl}”. Sentences of target languages can also be stored in the UNL document. Each target sentence is enclosed with a pair of language tags “{<lang>}” and “{</lang>}” following the UNL expression of each sentence.
| Tag | Description |
|---|---|
| [D:<id>] | indicates the beginning of a document. |
| [/D] | indicates the end of a document |
| [P:<id>] | indicates the beginning of a paragraph. |
| [/P] | indicates the end of a paragraph |
| [S:<id>] | indicates the beginning of a sentence. |
| [/S] | indicates the end of a sentence |
| {org:<lang>=<code>} | indicates the beginning of an original/source sentence |
| {/org} | indicates the end of an original sentence |
| {unl:<id>} | indicates the beginning of the UNL expressions of a sentence. |
| {/unl} | indicates the end of the UNL expressions of a sentence |
| {<lang>} | indicates the beginning of a target sentence of the language indicated by <lang> |
| {/<lang>} | indicates the end of a target sentence of the language indicated by <lang> |
- Where
- :<id> (optional), which is normally represented by an integer, may be any sequence of characters used to identify the document, the sentence, the paragraph or the UNL expression
- <lang> (optional in case of {org}) corresponds to the language code in ISO639-2 or ISO639-3
- =<code> (optional) corresponds to the character encoding
Semantics
For the time being, a UNL document is simply a collection of UNL sentences. However, it can also be treated as a hypergraph itself, comprising several subhypergraphs (the UNL sentences) inter-related by a special relation "nxt" (for "next"), which indicates sequential order. In the XUNL Project, we have been proposing some other strategies for representing cross-sentential relations, which are, however, still under discussion.
