Storing Matlab objects in hdf5

Dear Forum,

I am trying to store Matlab objects in a compound datatype table, i.e.
every instance goes into one row. In doing this, I encounter some
problems/ questions:

1. Assume the object contains a property with a 1D-array, which I would
intuitively map to a variable length type, e.g.
H5T.vlen_create('H5T_NATIVE_DOUBLE'). Unfortunately the array can lose
orientation after store/ restore, since the hdf array does not know
horizontal/ vertical allignment. Is there a recommended procedure in
order to preserve the orientation?

2. Assume the object contains a matrix property whereat the matrix size
may change over instances. I cannot figure out, if this can be handled
by means of a compound data set. Is this in general possible? Is there a
better solution than compound?