Please consider the following new default values.

[James Hester]

Dear Core DMG,

A number of new default enumeration values were introduced in the new DDLm
dictionary which are not present in the old DDL1 dictionary. Could you
please consider whether or not they are reasonable and comment either here
or at Github.  A lack of comments will lead to Antanas and I likely erring
on the side of caution and removing those that are not obviously correct.

I reproduce Antanas' list and comments below (html format). If this is
unreadable, please view the original at
https://github.com/COMCIFS/cif_core/issues/58.

James.
===

*1. Experimental*
ID Data name Default
1.1 _exptl_crystal_density_meas_temp 293.
1.2 _exptl_crystal_density_meas_temp_lt 293.
1.3 _exptl_crystal_density_meas_temp_gt 293.
1.4 _exptl_crystals_number 1
1.5 _exptl_absorpt_correction_type none
1.6 _exptl_crystal_colour_primary white

The _exptl_crystals_number and _exptl_absorpt_correction_type seem
reasonable, but should
exptl_crystal_density_meas_temp_* and_exptl_crystal_colour_primary have
default values at all?

*2. Atom sites solution*
ID Data name Default
2.1 _atom_sites_solution_hydrogens difmap
2.2 _atom_sites_solution_primary direct
2.3 _atom_sites_solution_secondary difmap

*3. Diffraction radiation*
ID Data name Default
3.1 _diffrn_radiation_wavelength_determination fundamental
3.2 _diffrn_radiation_probe x-ray
3.3 _diffrn_radiation_xray_symbol K-L~3~
2.4 _diffrn_radiation_source tube
3.5 _diffrn_source_target Cu

Note: the _diffrn_radiation_source data item has only become an enumerator
value in the DDLm version of the dictionary. It is more thoroughly
discussed in issue #59 <https://github.com/COMCIFS/cif_core/issues/59>.

*4. Reflections*
ID Data name Default
4.1 _refln_[A|B|F|F_squared]_calc 0
4.2 _refln_[A|B|F|F_squared]_meas 0
4.3 _refln_[F|F_squared]_sigma 0

*5.Diffraction reflections*
ID Data name Default
5.1 _diffrn_refln_scan_mode ot
5.2 _diffrn_refln_scan_mode_backgd st

*6.Chemical*
ID Data name Default
6.1 _chemical_enantioexcess_crystal_technique CD
6.2 _chemical_enantioexcess_bulk_technique OA
6.3 _chemical_absolute_configuration .

*7.Refinement*
ID Data name Default
7.1 _atom_site_refinement_flags .
7.2 _atom_site_refinement_flags_adp .
7.3 _atom_site_refinement_flags_posn .
7.4 _atom_site_refinement_flags_occupancy .

Seems reasonable since the lack of these data items imply that the related
techniques were not applied thus resulting in a '.' (inapplicable) special
value.

*8.ADP*
ID Data name Default
8.1 _atom_site_adp_type Uiso

Seems reasonable.

*9.Crystal system*
ID Data name Default
9.1 _space_group_crystal_system triclinic

This addition seems a bit strange. Might it be related to the removal of
the default *cell_angle** values (discussed in #57
<https://github.com/COMCIFS/cif_core/issues/57>)?

*10.Bibliography*
ID Data name Default
10.1 _journal_page_first 1
10.2 _publ_body_element section
10.3 _journal_index_type O
10.4 _citation_coordinate_linkage yes
-- 
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F +61 (02) 9717 3145
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