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Data Transfer
Format Mode Data Transfer
The following paragraphs contain detailed information on the data fields recognized by Format
mode, checks made on the fields before data transmission, the data block start point, and the
type of data transferred.
FIELDS. The start point for a field is defined by a ««start field" indicator. A ««stop field" indicator
defines the end of the field. A single field may extend beyond one line or row; such a field is
called a continued field. For a continued field, a start field indicator is used in the first column
of the second and each consecutive line occupied by the field. A stop field indicator is used at the
end of the field.
If a start field is not in column 0 of a line following one containing a field with no stop field, the
end of that line is the implicit end of field. No explicit stop field is needed.
The field separator or block terminator, as selected on the Terminal Configuration menu, is
transmitted after· the contents of the field, as would occur normally.
FIELD CHECKS. Two field attributes, the ««required" attribute and the ««modified data tag",
are checked after the. key is pressed or at transmission time. Other attributes are checked
when the fields are being filled by the user or when the field is to be exited.
Before the. keystroke is acknowledged, a check is done to ensure that all ««required" fields
have data entered in them. This check is done before any cursor repositioning and before any
handshaking is done. They must all be in this state, even though none would be transmitted,
given the current mode conditions and cursor position.
The <<<required" field check is not done for the ««send display"
(Ec d)
data transfer.
CLEARING OF TERMINATORS. Non-displaying terminators are cleared when tabbed
over or when a <<<clear display" operation is executed. They are not cleared, however, when a
cursor-move keystroke or cursor-movement escape sequence is executed.
Block'terminators, like normal characters, are not cleared by tabbing.
START POINT. When in Block mode with the
Au
t
0
Term<
J)
strap set, the search backward for
a block terminator or non-displaying terminator includes the protected fields. If a terminator
is found in a protected field, the block transfer begins at the start of the next unprotected field.
This is not a likely event, however.
Unlike the non-Format mode case, a memory locked area is searched (after the workspace is
adjusted completely) and is treated as the rest of the workspa·ce is. This is the case also for
<<<home up"; the memory-locked area is only special in Format mode, in that it does not roll up or
down.
DATATRANSMITTED. In Format mode, only the ASCII characters (both control codes and
displayable characters) in unprotected fields are transmitted.
When the terminal is configured to send only "modified" fields, data compression is performed.
~
When in Character, Block Line, and Block Page modes, trailing blanks are eliminated from the
field contents.
9-10
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