Ray,

> Our Group asked me to follow up the issue you reported.  I understand that 
> you want to declare a dimension size to be zero and you won't write any data 
> to it.  A data space with zero dimension size is totally empty.  It only 
> shows the number (or rank) of the dimensions.  Is this correct?

Almost. Such a dataspace is indeed empty (no data), but it still contains more 
information than the rank:
1) The datatype
2) The size of each dimension, of which at least one is zero.

Point 2) is the main difference to H5S_EMPTY. It is useful to have the full 
dimension information to avoid introducing special cases into applications.

An example: suppose my data model specifies that the coordinates of N points 
are stored in an array of type float and dimension [N 3]. A validator for this 
data model would then check that the size of the second dimension is 3, which 
should be possible even if N happens to be zero.

Konrad.
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Konrad Hinsen
Centre de Biophysique Moléculaire, CNRS Orléans
Synchrotron Soleil - Division Expériences
Saint Aubin - BP 48
91192 Gif sur Yvette Cedex, France
Tel. +33-1 69 35 97 15
E-Mail: research AT khinsen DOT fastmail DOT net
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