NSS orbital models compatible with two-body solution

This covers astrometric binaries, spectroscopic binaries, eclipsing binaries and certain combinations thereof. Several possible models are hosted within the same table and they are indicated by the field <code>nss_solution_type</code>.

The description of this latter lists all possible solution types considered for this release. Only a selection of parameters hosted in this table are provided here, depending on the solution. The details of those is given in the description of field <code>bit_index</code>, which can also be used to extract the relevant elements of the correlation vector <code>corr_vec</code>.Details about the formalism used to derive the parameters in this table are given in the on-line documentation, see Chapter&nbsp;<a href="chap:cu4nss">cu4nss</a>.