This function is meant to enable the parallel writing (with multiple threads) of several type 9 segments (discrete states of the positions and velocities, Lagrange interpolation with unequal timesteps) to the SPK file associated to the ephemeris descriptor *eph*.

It reserves space in the file for *target_count* segments, each segment associated to a target in the *targets* array.
Each target has its own number of records specified in the *record_counts* array, and its own segment identifier specified in the *segids* array.
All the targets share the same *center*, *frame*, *start_..._tdb*, *end_..._tdb* and *deg* parameters.

The array *targets*, *record_counts* and *segids* must be of size *target_count*.

The reservation *id* returned by this function must be used in the function |writeph_spk9_par_write| to write in the corresponding reserved space.
In addition, the function |writeph_spk9_par_write| will require a *target_index*, which is the index of the target in the *targets* array used in this function.

A call to *writeph_spk9_par_reserve* is always performed by a single thread and is followed by several calls to |writeph_spk9_par_write| by one or several threads.

.. include:: examples/writeph_spk9_par_reserve.rst