IBM 3164 ASCII Manual page 96

Note: The field data has the same format as the send/read page data stream.
The read all format for the unformatted page works like in the following way.
When the Read All command is received in the unformatted page, the display
station performs the same function as the Send/ Read Page command. In this
case, character attributes are always sent to the host.
The read all format for the formatted page looks like this:
I
~.--------Text---------~·I
Field
Field
Data 1 Data 2
(
)
Field
Data i
Field
Data n
LTA
The data is sent from the first character position in the page, even if the field
wraps from the last character position to the first character position in the
page. As a result, the first field data does not include the SFA response.
Data conversion (main port)
All graphic characters are transmitted to the host without data conversion.
Whenever a graphic character stored in a character set different from that of
the previously transrr,itted character is encountered, the Select
GO/G1
response and/or the SI/SO control character is applied just prior to sending
that graphic character.
All ASCII control characters (except Null) are sent to the host without data
conversion. If the Null Suppress option is on, the trailing null characters are
suppressed and other nulls are converted to space characters before
transmission. If the Null Suppress option is off, all nulls are converted to
space characters and then transmitted to the host.
A field attribute character is sent to the host in the format of the Set Field
Attribute response.
A character attribute is sent in the format of the Set Character Attribute
response.
A line attribute is sent to the host in the format of the Set
SHDW/DHSW/DHDW response.
An error symbol is converted to a space character and the send mark (
~
) is
treated as a null character.
Text format (auxiliary port)
When a Print key is pressed or a Print (Print Viewport/Screen/Page/Message
/ Line) command is received, the ASCII graphic characters, subscripts,
superscripts, line-draw, and alternate characters are sent to the auxiliary port
without data conversion. The field-attribute characters and the characters in
the non-display fields are converted to space characters. The send mark, error
symbol, and null characters are also converted to space characters.
5-9