For the developers, in order DR_HOOK to run, each subroutine has to contain several further instructions :
USE YOMHOOK, ONLY : LHOOK, DR_HOOK USE PARKIND1, ONLY : JPRB
REAL(KIND=JPRB) :: ZOOK_HANDLE
Then, just after declarations : IF (LHOOK) CALL DR_HOOK(’name of the subroutine’,0, (...)