Re: 1.8 file format

[John Caron <caron@xxxxxxxxxxxxxxxx>]

>     Hmm, looks like the docs are out of date and/or wrong for region 
> references.  Because region references are variable in length, the 
> actual reference information is stored in the global heap and a (fixed 
> length) heap ID is stored in the dataset's raw data - that part is 
> right, although too briefly described.  

the data storage layout messaage seems to imply the HeapID is 12 bytes long. Usually they are 16 bytes long.

   type = Layout(8); contiguous storageSize = (2,12) dataAddress=13352

I dont see enough detail in h5dump:

        DATASET "VIIRS-NCC-EDR_Gran_0" {
           DATATYPE  H5T_REFERENCE
           DATASPACE  SIMPLE { ( 2 ) / ( 2 ) }

is there another option that would verify that?

in any case is 12 bytes correct? if so, what does a 12-byte HeapId look like?

The format of the data in the 
> heap is wrong however.  The information actually stored in the heap is 
> as follows:
>     - The offset of the object header of the object (ie. dataset) 
> pointed to (yes, an object ID)
>     - A serialized form of a dataspace _selection_ of elements (in the 
> dataset pointed to).  I don't have a formal description of this 
> information now, but it's encoded in the H5S_<foo>_serialize() routines 
> in src/H5S<foo>.c, where foo = {all, hyper, point, none}.
>
>     There is _no_ datatype information stored for these sort of 
> selections currently.
>
>     I'll file a bug report in our bugzilla to make certain this 
> description gets fixed in the file format spec.
>
>     Quincey

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