chart:axis-type="date"

Hi,

    
I think I finally understand the problem chart:axis-type="date"
      is suppsed to address:

    
Some charts, for example the chart:bar class, have an axis that
      is predefined to be either a categories axis (i.e. category labels
      are evenly spaced and the corresponding values are shown at these
      evenly spaced locations) or a value axis (i.e. values are shown at
      their relative locations).

    
For example for a barchart with x-values that are dates (years ),
      e.g. 1950,1980, 2000, 2010, with a category type axis the 4 bars
      would be evenly spaced as if at values 1,2,3,4 with these points
      on the x axis labelled 1950,1980, 2000, 2010. If we had the same
      chart type but with a value type x-axis the bars would not be
      evenly spaced since the difference between 1950 and 1980 will be
      three times as large as the difference between 2000 and 2010.

    
I believe Regina's suggestion is to obtain the second chart by
      labelling flagging the second axis as chart:axis-type="date".

    
To me all of this has nothing to do with dates. These values
      1950,1980, 2000, 2010 simply differ from other categories like
      a,b,3,d that they are all numbers and so can be interpreted as
      relative locations on the x-axis.

    
So since there is nothing special about dates being involved
      (except that apparently Excel allows the second type of chart only
      for date values) I believe we should not make this date specific,
      but simply flag axis with their type (if it differs from their
      default type), e.g. chart:axis-type="values" or
      chart:axis-type="categories" or chart:axis-type="value-preference"
      where the last type means that if all values/categories given are
      numbers then the axis behaves like a value axes (placing items in
      their relative position) and like a categories axis otherwise.

    
Andreas

    

    

    
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