IBM 3270 User Manual page 40

In like manner, set tab stops at the other two X positions. If you
accidentally set a tab stop at an incorrect position, you can clear it
by placing the cursor under it and pressing the Delete Character
( 'I)
key. We will use "these tab stops in a minute.
1. Move the cursor along the scale line until it lines up about five
positions to the left of the right margin and type the
*
symbol.
This causes the 'end of line' signal to be set at that position of
the line. We will use the signal in a minute. (You clear the 'end
of line' signal by placing the cursor under it and pressing the
Delete Character (
'I )
key.)
2. Press the CHG FMT key to exit from change format mode.
(The scale line disappears.)
Now we have margins, tab stops, and an 'end of line' signal set up.
Let's try them.
Use the spacebar to move the cursor along the following blank line,
and note that the 'end of line' signal sounds as the cursor passes
through the signal position on the line.
Now return the cursor to the left margin and press the Tab key.
Note how the cursor moves to the next tab stop (which you have
just set). Press the Tab key a few times and note how the cursor
moves from tab stop to tab stop. Hold the Tab key down and note
that the cursor stops not only at tab stops but also at other positions
on the line. These other positions are unprotected fields, and the
cursor stops at them just as it always did when you used the Tab
key.
Now try the Backtab key
(1eftward~pointing
arrow just above'the
New Line key) and note that the cursor stops at the same positions
as it moves in the reverse direction.
Use these keys to move the cursor around to get a feel for how they
operate.
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