[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Reply to: [list | sender only]
Re: [ddlm-group] CIF header
- To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
- Subject: Re: [ddlm-group] CIF header
- From: David Brown <idbrown@mcmaster.ca>
- Date: Wed, 28 Oct 2009 09:38:49 -0400
- In-Reply-To: <279aad2a0910271602j43777cf8xb2d8b9cf2d2d5cb9@mail.gmail.com>
- References: <4AE70F95.5000702@niehs.nih.gov><279aad2a0910271602j43777cf8xb2d8b9cf2d2d5cb9@mail.gmail.com>
I agree that a header is needed. I am concerned about starting it
with a # which could still get lost, though I can find no good example
of where it would cause a problem. However, as a matter of principle I
think it bad form to have a convention (# = comment) that applies
everywhere except in this one location. Almost any other character
would do but this might upset CIF1 parsers. I suppose the real
advantage of starting with # is that it would be ignored by a legacy
CIF1 parser without causing a problem (though the parser might have
problems later). David James Hester wrote: I believe that Joe's suggestion of mandating a CIF2.0 header comment coincides with Brian's earlier suggestion that this should now be mandatory. We should also note David's comment that we must now be careful about stating that comments can be discarded from files, as the first line comment may be a special case. Regarding David's comment, I think that we can proceed by stating that any program that writes a CIF must put in the mandatory CIF2.0 (or whatever it turns out to be) comment in the header. This would include programs that simply strip comments and then write something out. Are we all agreed on having a mandatory header? On Wed, Oct 28, 2009 at 2:19 AM, Joe Krahn <krahn@niehs.nih.gov> wrote:IMHO, there should be some sort of header to distinguish CIF variants, sort of like the DOCTYPE line at the top of XML files. This will help deal with CIF1 files that are not CIF2 compliant, and could also better handle more extreme variants, like binary CIF. The current syntax suggests, but does not require, an initial comment line starting with #CIF. I proposed to the COMCIFS list that global_ could be used for this purpose. In this way, global_ would only be read by the parser, and not be considered as part of the actual CIF data. The idea is to use the existing STAR syntax instead of designing something new. The disadvantage is that the global_ section itself would have to maintain a restricted 7-bit ASCII format, and not allow any of the newer STAR/CIF syntax. So, the "simplicity" of just using the existing STAR syntax really is not there. Alternatively, the initial CIF comment line could be made a requirement rather than a suggestion, and also define a way to include additional file attributes in the form of param=value pairs. For example, a CIF2 file could add "binary=true" to indicate the presence of binary sections, rather than binary-CIF having to be a completely separate format. If extra file attributes seem like an unnecessary complication, then maybe at least the simple comment line could be made a requirement? Then, you can distinguish CIF2 files, and assume that any file without a comment is CIF1. Joe Krahn _______________________________________________ ddlm-group mailing list ddlm-group@iucr.org http://scripts.iucr.org/mailman/listinfo/ddlm-group |
begin:vcard fn:I.David Brown n:Brown;I.David org:McMaster University;Brockhouse Institute for Materials Research adr:;;King St. W;Hamilton;Ontario;L8S 4M1;Canada email;internet:idbrown@mcmaster.ca title:Professor Emeritus tel;work:+905 525 9140 x 24710 tel;fax:+905 521 2773 version:2.1 end:vcard
_______________________________________________ ddlm-group mailing list ddlm-group@iucr.org http://scripts.iucr.org/mailman/listinfo/ddlm-group
Reply to: [list | sender only]
- Follow-Ups:
- Re: [ddlm-group] CIF header (Nick Spadaccini)
- Re: [ddlm-group] CIF header (James Hester)
- References:
- [ddlm-group] CIF header (Joe Krahn)
- Re: [ddlm-group] CIF header (James Hester)
- Prev by Date: Re: [ddlm-group] CIF header
- Next by Date: Re: [ddlm-group] Relationship of CIF2 to legacy platforms
- Prev by thread: Re: [ddlm-group] CIF header
- Next by thread: Re: [ddlm-group] CIF header
- Index(es):