FORTRAN Reference Manual

Run-Time Diagnostic Messages
FORTRAN Reference Manual—528615-001
G-2
START BACKUP and CHECKPOINT Errors
can determine if an error occurred and, if so, its error number, by analyzing the value in
ios.
If you specify label but not ios, your program continues executing with the
statement labeled label. Although your program can detect that an error occurred—
by the fact that it is now executing at a specified label—you cannot determine the
specific error that occurred.
If you specify both label and ios, FORTRAN transfers control to label and you can
determine the error that occurred by the error number in ios.
If you do not specify label or ios, FORTRAN terminates your program and writes an
error message to the log file.
FORTRAN utility routines include a positional parameter in which the routine stores an
error number. If an error occurs and you do not specify the error parameter, FORTRAN
terminates your program and writes an error message to the log file.
START BACKUP and CHECKPOINT Errors
Both the START BACKUP and CHECKPOINT statements include a
BACKUPSTATUS= specifier, as well as an ERR= specifier. These specifiers serve the
same purpose for START BACKUP and CHECKPOINT statements as IOSTAT and
ERR do for I/O statements.
If ENV OLD is in effect and an error occurs when your program executes a START
BACKUP or CHECKPOINT statement that does not include a BACKUPSTATUS=
specifier, the FORTRAN run-time library writes a message to your terminal. Your
program continues running either with the executable statement designated in the
ERR= specifier, or, if you do not specify ERR=, with the executable statement following
the START BACKUP or CHECKPOINT statement.
If ENV COMMON is in effect and an error occurs when your program executes a
START BACKUP or CHECKPOINT statement that does not include a
BACKUPSTATUS= specifier, the FORTRAN run-time library writes a message to the
standard log file. If the START BACKUP or CHECKPOINT statement includes an
ERR= specifier, your program continues running at the label specified in the ERR=
specifier. Otherwise, the run-time library terminates your program.