Up to now, in order to indicate the brand new syntax off RIF-FLD we made use of “mathematical English,” another type of kind of English to have connecting analytical definitions, examples, etc. The following circumstances concerning the EBNF notation are kept in mind:
LOCATOR
- This new syntax out of RIF-FLD depends on the fresh signature process which will be perhaps not framework-totally free, very EBNF does not take that it syntax precisely. Consequently, the EBNF sentence structure represent a rigid superset regarding RIF-FLD (never assume all formulas that are derivable using the EBNF grammar try well-formed).
- The EBNF syntax is not a concrete syntax: it does not address the details of how constants (defined in [RIF-DTB]) and variables are represented, and it is not sufficiently precise about the delimiters and escape symbols. White space is informally used as a delimiter, and is implied in productions that use Kleene star. For instance, TERM* is to be understood as Title Term . Term, where each ‘ ‘ abstracts from one or more blanks, tabs, newlines, etc. This is done intentionally since RIF’s presentation syntax is used as a tool for specifying the semantics and for illustration of the main RIF concepts through examples.
- RIF represent a concrete sentence structure only for buying and selling regulations, which sentence structure is actually XML-built, obtained just like the an elegance and you can serialization of EBNF syntax via the fresh new speech-syntax-to-XML mapping to possess RIF-FLD.
Remaining these planned, brand new EBNF sentence structure is visible given that only an intermediary between the newest mathematical English together with XML. But not, in addition brings a succinct view of the latest syntax out of RIF-FLD and therefore can be handy for dialect music artists and pages the exact same.
Per RIF-FLD algorithm and name should be prefixed having that optional annotation
The RIF-FLD presentation syntax does not commit to any particular vocabulary and permits arbitrary sequences of Unicode characters in constant symbols, argument names, and variables. Such sequences are denoted with UNICODESTRING in the above what is airg syntax. Constant symbols have this form: "UNICODESTRING"^^SYMSPACE, where SYMSPACE is a ANGLEBRACKIRI or CURIE that represents the identifier of the symbol space of the constant. UNICODESTRING, ANGLEBRACKIRI, and CURIE are defined in Section Shortcuts for Constants in RIF’s Presentation Syntax of [RIF-DTB]. Constant symbols can also have several shortcut forms, which are represented by the non-terminal CONSTSHORT. These shortcuts are also defined in the same section of [RIF-DTB]. One of them is the CURIE shortcut, which is used in the examples in this document. Names are Unicode character sequences that form valid XML NCNames [XML-Names]. Variables are composed of Names prefixed with a ?-sign.
, which is used in several places in the grammar, is a non-terminal whose definition is left to the dialects. It is intended to specify the protocol by which external sources, remote modules, and imported RIF documents are located. This must include the basic form
The symbols NEWCONNECTIVE, NEWQUANTIFIER, NEWAGGRFUNC, and NEWTERM are RIF-FLD extension points. They are not actual symbols in the alphabet. Instead, dialects are supposed to replace NEWCONNECTIVE, NEWQUANTIFIER, and NEWAGGRFUNC, by zero or more actual new symbols, while NEWTERM is to be replaced by zero or more new kinds of terms. Note that the extension point NEWSYMBOL is not shown in the EBNF grammar completely avoids mentioning the alphabet of the language (which is infinite).
IRIMETA, for identification and metadata. IRIMETA is represented using (*. *)-brackets that contain an optional rif:iri constant as identifier followed by an optional Physical stature or cones as metadata. One such specialization is '"' IRI '"^^' 'rif:iri' from the Const production, where IRI is a sequence of Unicode characters that forms an internationalized resource identifier as defined by [RFC-3987].