An FCONTROL call with a controlcode
value of 25 is used to establish an Additional End-of-Record (AEOR)
character, which is then in effect for reads posted against the
device that owns the file whose file number is specified in filenum.
You can only assign one AEOR character at a time. If you need more
than one AEOR, use FDEVICECONTROL instead.
Normally, character mode reads using standard editing are
terminated by a carriage return ([Return]), the
standard EOR character for HP terminal types. The system echoes
the carriage return and sends a linefeed to the terminal, so that
the cursor is positioned at the beginning of the next line, ready
for the next read. Even if an AEOR character has been assigned by
a call to FCONTROL(25), the EOR character will still terminate reads
in the usual way.
When a read is terminated by an Additional End-of-Record character,
the AEOR character is included in both the data and in the byte
count. No carriage return or linefeed is sent to the terminal. The
read terminates with an error condition which indicates that the
Additional End-of-Record character has been encountered. A call
to FCHECK returns an error code of 31. To recover from this error,
your program can delete the AEOR character from the input data,
subtract one from the byte count of the read, and send out a carriage
return and linefeed to place the cursor in the proper place for
the next read.
An AEOR character designated by FCONTROL(25) is also recognized
as a line terminator during reads in transparent editing mode, along
with a user defined EOR character that replaces [Return]
as the normal EOR character.
See the discussion of FCONTROL(41) later in this chapter for
more information on terminating reads in transparent mode.
To disable the Additional End-of-Record character, call FCONTROL(25)
again specifying 0 as the value of param.
There are a number of characters that will not be recognized
if used as AEOR characters, as listed in Table 8-4 “Characters
Not Recognized If Used as AEORs”. You will receive no error message if
you use one of these characters, but the character will not terminate
a read if entered.
