Re: [h5md-user] Modules

[Peter Colberg]

On Wed, Sep 18, 2013 at 05:27:14PM +0200, Konrad Hinsen wrote:
> OK, here's a proposition. I have added a version number to Olaf's
> original specification. Everything is likely to change with time, so
> version numbers have their use.
> 
> The storage of module information is of course debatable. I like
> tables using compound data types, but others hate them. Personally I
> don't really care, so if someone sees a good reason to store the
> information otherwise, that's fine with me.

Then, how about using one subgroup per module, as follows:

------------------------------------------------------------
Modules

The H5MD specification can be complemented by domain-specific modules,
which add conditions that the data in the H5MD file must satisfy,
and rules for the semantic interpretation of the data. A single
trajectory can use multiple modules, as long as their prescriptions
are not contradictory. Each module is identified by a name and a
version number.

The modules that apply to a specific H5MD file are stored as subgroups
within the group h5md/modules. A module holds as an attribute the
version number stored as an integer.

    h5md
     \-- ...
     \-- (modules)
          \-- <module1>
          |    +-- version
          \-- <module2>
          |    +-- version
          \-- ...

------------------------------------------------------------


The use of subgroups supports adding module-specific attributes. For
a unified "units" module, for example, the specific unit system could
be specified as a module attribute, e.g.,

    h5md
     \-- ...
     \-- (modules)
         \-- units
               +-- version
               +-- system

where "system" contains, e.g., the string "SI" for SI units. But I
will write no further on the topic of units, since I am not qualified
as a user of Lennard-Jones units…

Peter