The units of PVAJ.
This integer is a sum of some unit constants (CALCEPH_UNIT_???) and/or the constant
CALCEPH_USE_NAIFID.If the unit contains
CALCEPH_USE_NAIFID, the NAIF identification numbering system is used for the target and the center (NAIF identification numbers for the list).If the unit doesnot contain
CALCEPH_USE_NAIFID, the old number system is used for the target and the center (see the list in the function f90calceph_compute()).