{ The Pascal OPEN statement does not allow the record type to be RMS        }
{ "undefined" record type.  In order to create such a file from Pascal, you }
{ must use a user-action routine as demonstrated below.  Object files on    }
{ OpenVMS I64 used the "undefined" file format since they are pure byte     }
{ stream files.  Using "undefined" allows you to append multiple object     }
{ together into a ".OBS" file that can be processed by the linker.  If      }
{ another format was chosen, like fixed-length 512-byte records, single     }
{ .OBJ files work correctly, but when concatenated together, the extra room }
{ at the end of each .OBJ file gets inserted between the files in the final }
{ .OBS file making it unusable.                                             }

[INHERIT('sys$library:starlet')]
PROGRAM Create_UDF_File(INPUT,OUTPUT);

TYPE
    Header_Type = PACKED RECORD
                  F1 : INTEGER;
	          F2 : [WORD] 0..65535;
	          F3 : INTEGER;
	          F4 : [BYTE] 0..255;
	          END;

VAR
    Buffer    : VARYING [255] OF CHAR;
    Filename  : VARYING [132] OF CHAR;
    F         : TEXT;
    Header    : Header_Type;

{ Use a USER_ACTION routine to set the FAB$B_RFM to FAB$C_UDF. }

FUNCTION User_Action( 
    VAR Fab : FAB$Type;
    VAR Rab : RAB$Type;
    VAR F : TEXT
    ) : INTEGER;

    VAR
	Status : INTEGER;

    BEGIN

    { Set the record format to UDF overwriting the VAR }
    { format that was set by the RTL since the file is }
    { a TEXT file.                                     }

    Fab.FAB$B_RFM := FAB$C_UDF;

    { Do the $create }
    Status := $create(Fab);
    IF ODD(Status)
    THEN
	BEGIN

	{ The $open was successful, now do the $connect }
	Status := $connect(Rab);
	END;

     { Return status from $open/$connect }
     User_Action := Status;
     END;

    BEGIN
    WRITE('Filename? ');
    READLN(Filename);
    OPEN(File_Variable := F,
	 File_Name     := Filename, 
	 History       := New, 
	 Carriage_Control := None,
	 User_Action   := User_Action);
    REWRITE(F);

    { Since the file is defined as TEXT, we can write variable length things }
    { to it using a VARYING string as a temporary buffer. We need to use     }
    { variable length write statements to RMS can accurately keep track of   }
    { the file's end-of-file-block and end-of-file-block's last used byte.   }
    { Use the DUMP/HEADER DCL command to examine the end-of-file block and   }
    { end-of-file byte values.  They are not displayed by DIRECTORY/FULL     }

    Header.F1 := 16#12344321;
    Header.F2 := 16#ABCD;
    Header.F3 := 16#FEDCBA98;
    Header.F4 := 16#FF;

    Buffer.body::Header_Type := Header;
    Buffer.length            := size(Header);

    WRITE(F,Buffer);
    CLOSE(F);

    END.