On Fri, 2013-09-20 at 17:30 +0100, Marcin Wojdyr wrote: > On Fri, Sep 20, 2013 at 11:51:57AM +0100, Peter Keller wrote: > > > The STAR grammar in chapter 2.1 is the accurate one. If you look at page > > 18, you will see that the productions for quoted text strings are > > completely different from the ones in chapter 2.2. > > Different, but look equivalent to me.
In principle, they should be equivalent, but in practice as I explained the CIF grammar has at least one ambiguity that doesn't exist in the STAR grammar .... > But clearly there are differences between STAR and CIF grammars. > I'm not interested enough in these format to continue this thread > much longer. When I was writing CIF parser 5 years ago I also had > impression that there are mistakes in the CIF spec. .... and probably errors too, as you have noticed. > If that's true, > IMO listing (and then fixing) these mistakes can prevent different > CIF dialects. Well, by itself that is not sufficient, but it would certainly help. I'm not sure that there is anyone around who has both sufficient clout and also the interest to make sure that those fixes become authoritative, although I have no objection to being proved wrong about that of course. CIF has been around a long time, and the fact that ambiguities and errors in the specification can still form a subject for discussion seems unfortunate to me. > Recommending STAR spec as extra reading can't. Like you I think that this thread is becoming unproductive, but I have to close by insisting that the STAR spec has an important role to play in the (mm)CIF developers' world at the present time, because: * All CIF data has to conform to the STAR syntax (Int Tab G, section 2.2.1). * The STAR specification as far as I can see is free of errors and ambiguities. Therefore, the STAR spec is authoritative as far as the lexical and syntactical aspects of CIF are concerned (although clearly not for semantic issues). Regards, Peter. -- Peter Keller Tel.: +44 (0)1223 353033 Global Phasing Ltd., Fax.: +44 (0)1223 366889 Sheraton House, Castle Park, Cambridge CB3 0AX United Kingdom
