'Data file prem-crt.dat: Ray tracing in PREM'
'prem-mod.dat'
' '                   (Data set prem-dcr.dat is included in this file)
' '                   (Data set prem-ini.dat is included in this file)
'prem-cod.dat'
'prem-rpa.dat'
'prem-wri.dat'
'prem-log.out'

'prem-dcr.dat'
2   0   5   0 /         (KSTORE, NEXPS, NHLF, MODCRT)
 2.0 10.0 0.005 0.100 0.100 0.100 0.000 / (STORE, STEP, error bounds)
/                       (computational volume is the whole model)
/                       (no auxiliary surface)
/                       (no end surfaces)
1 1 /                   (storing surfaces)
1 2
1 2

'prem-ini.dat'
-1 2 /                (Single initial point, geographic-like sph.coor.)
'prem-src.dat' /      (Name of the file with source coordinates)

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