[CF-metadata] Add new integer types to CF?

Manning, Evan M (398B) Evan.M.Manning at jpl.nasa.gov
Fri Sep 22 11:36:20 MDT 2017

I think the _Unsigned attribute would have been a grand idea before.

But if we’re now allowing explicit unsigned types, what purpose does it serve?  

Do I use the _Unsigned = “true” attribute on every ubyte, ushort, and uint variable?  They’re already clearly unsigned according to the type definition.

it would only be useful if I wanted to keep declaring the variables as byte but wanted folks to treat them as ubyte.  This seems perverse.

And would we start putting _Unsigned = “false” on all of our integer variables?  All numeric variables?

Also note that fully supporting the new types means we can have unsigned integer global attributes.  Since attributes can’t have attributes, _Unsigned and valid_ don’t help here.

  -- Evan

On 9/22/17, 9:55 AM, "Signell, Richard" <rsignell at usgs.gov> wrote:

    I suggested
    _Unsigned = "true"
    because that is  already supported by Unidata:
    @Unidata: are you guys are you going to chime in on this?
    On Fri, Sep 22, 2017 at 12:40 PM, Charlie Zender <zender at uci.edu> wrote:
    > _Unsigned = "true" is cleaner and clearer to me
    > than the valid_* attributes.
    > To me, Rich's suggestion requires a consensus
    > to _drop_ valid_* in CF 1.8, and instead make
    > _Unsigned the preferred workaround for file formats
    > that do not support unsigned types.
    > Unless people want to require _both_
    > _Unsigned and valid_* (seems burdensome to me),
    > or allow either _Unsigned or valid_* (seems
    > crufty to me). What do others think?
    > On 9/22/17 04:49, Signell, Richard wrote:
    >> lookin at the NUG, how about saying:
    >> In file types that don't offer native support for unsigned types,
    >> integer or byte variables that are to be interpreted as unsigned must
    >> have the attribute _Unsigned = "true".
    > --
    > Charlie Zender, Earth System Sci. & Computer Sci.
    > University of California, Irvine 949-891-2429 )'(
    Dr. Richard P. Signell   (508) 457-2229
    USGS, 384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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