[geos-devel] GEOS Exceptions

[Artem Pavlenko]

strk at refractions.net wrote:

>On Tue, Apr 19, 2005 at 02:33:16PM +0100, Artem Pavlenko wrote:
>  
>
>>Hi Frank
>>
>>I think EMPTY means literaly empty
>>have a look at http://www.cl.cam.ac.uk/%7Emgk25/iso-14977.pdf
>>    
>>
>
>Actually, reading the grammar in OGC SFS 1.1 it doesn't look as
>EMPTY has a special meaning:
>
><Point Tagged Text> :=
>           POINT <Point Text>
>
><Point Text> := EMPTY | ( <Point> )
>
><Point> := <x> <y>
>
><x> := double precision literal
><y> := double precision literal
>
>
>Things with special meaning are wrapped in <> brackets or lowercase
>so that would be a <Empty> or 'empty sequence'.
>EMPTY looks like POINT, which is verbatim.
>
>  
>
Agree, it is ambiguous, yet ISO-EBNF lists EMPTY as a special keyword.
Can anyone ask OGC folks?
Artem