Empty Record Component #211
Description
It is in principle possible and valid to store a constant record component with extend attribute of zero, e.g. to document the attributes of a particle species with currently no "alive" particles.
It would make sense to explicitly define a "empty record component" just like the "constant record component" which makes the additional "value" attribute non-required, e.g. for types that cannot be simply be zero-initialized.
For zero-sized extends, arrays must be allowed such as [0, 0, 0, ], not only scalars [0, ]. This enables consistency of dimensionality of a record component over a time series.