Execution Sequence

  A program starts by executing the first executable statement of the main program unit. Execution continues sequentially unless control is transferred elsewhere: an IF or GO TO statement, for example, may transfer control to another part of the same program unit, whereas a CALL statement or function reference will transfer control temporarily to a procedure.

A program continues executing until it reaches a STOP statement in any program unit, or the END statement of the main program unit, or until a fatal error occurs. When a program terminates normally (at STOP or END) the Fortran system closes any files still open before returning control to the operating system. But when a program is terminated prematurely files, especially output files, may be left with incomplete or corrupted records.