Discussion List Archives

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [ddlm-group] Straw poll results

Dear All,

In this email I address the whole deprecation issue.  Nick: perhaps
you missed it, but the straw poll went in favour of immediately
setting a standard, with no deprecation, so the issue of deprecation
is now somewhat academic.  That new standard looks almost exactly like
you proposed, except for the addition of UTF8 and remaining doubts
around whitespace.

For the record, when proposing deprecation I envisioned a 1.2 standard
which looked like 1.1 except for the addition of brackets and triple
quoted strings -i.e. with only those changes that broke readers.  At
the same time as 1.2 was fixed, we also fix a 1.3 standard which
contains the additional changes that break writers, i.e. reduced
character set for non-delimited strings and removing embedded
delimiters. In the notes to the 1.2 standard and in the notes on the
1.1 standard, we insert statements to the effect that the 1.1
character set for non-delimited strings is deprecated and that all new
applications should use the productions contained in the 1.3 standard.
That is what I meant by deprecation: formal statements attached to the
standard stating that certain features are deprecated.  Of course the
BNF for each standard cannot communicate this information.

The purpose of this deprecation was to try to shepherd the CIF-writing
software community with us as we change the standard, by giving them
fair warning and, when the 1.3 standard comes into effect, hopefully
having a large body of conformant CIF1.3-writing software available.
However, the downside is that we have two new syntax standards instead
of one and increased potential for confusion, and in any case there
will be plenty of CIF1.1 files floating around from archives and the
consequent need to deal with them.

I believe Brian's proposal of making a single, clean, maximally
disruptive change to the standard and mandating a compulsory CIF1.2
header is therefore more reasonable.  It is entirely in the
community's hands as to when and if they make a transition to CIF1.2,
and rather than pushing and pulling them as I was envisioning, we rely
solely on making CIF1.2 easy to transition to (documentation, test
suites) and attractive as well (dREL, UTF8), without any hint of
coercion.  We insert deprecation notes into the CIF1.1 standard, and
explain how to write a CIF1.1 file that is also conformant to CIF1.2.
That way, any new CIF writing software should at least meet the new
standard.  We provide simple guides on the differences for parsers and
actively engage major CIF writing software packages.

The only suggestion I would make is that the new syntax is called
CIF2.0, in recognition of its disruptive nature.

T +61 (02) 9717 9907
F +61 (02) 9717 3145
M +61 (04) 0249 4148
ddlm-group mailing list

Reply to: [list | sender only]
International Union of Crystallography

Scientific Union Member of the International Science Council (admitted 1947). Member of CODATA, the ISC Committee on Data. Partner with UNESCO, the United Nations Educational, Scientific and Cultural Organization in the International Year of Crystallography 2014.

International Science Council Scientific Freedom Policy

The IUCr observes the basic policy of non-discrimination and affirms the right and freedom of scientists to associate in international scientific activity without regard to such factors as ethnic origin, religion, citizenship, language, political stance, gender, sex or age, in accordance with the Statutes of the International Council for Science.