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This subroutine handles the different forms of starting FLEXPART * depending on IPIN (set in COMMAND) * * IPIN=0: this routine is not called and particles are read from the * RELEASE option file * IPIN=1: restarting from a restart.bin file, written by a previous run * IPIN=2: restarting from a partoutput_xxx.nc file written by a previous * run, depending on what PARTOPTIONS the user has chosen, this * option might not be possible to use * IPIN=3: starting a run from a user defined initial particle conditions, * more on how to create such a file can be found in the manual * IPIN=4: restarting a run, while also reading in the initial particle * conditions * * Author: L. Bakels 2022 * *