3270setattribute

Refer to the 3270 Datastream Application Programming
Reference, and the CICS Application Programming Guide

Type Code Possible values and meaning
ATTRIBUTE X'C0' Same attribute bytes used with SF order (X'1d)'
COLOR x'2842' X'F1' to x'F7': Blue, Red, Pink, Green, Turq, Yellow, White
HILIGHT X'41' X'00' (No hilight) x'F1' (blink) x'F2' (reverse) x'F4'(underline)
OUTLINE X'C2' From X'00' to X'0F', in any combination of the following values: x'01' (under), x'02' (right), x'04'(over), x'08'(left)

So, if we want our arrow in the above example to be yellow, we
need to specify a colour code x'42' followed by the yellow value
x'F6'. And we must also indicate the basic attribute that makes
the field protected (X'F8') preceded by the attribute indicator
x'C0'. This gives us two byte pairs in our SFE order, which
means the order will be:
x'29Ø242F6CØF8' (SFE: 2 byte pairs) (colour: yellow) (attrb: prot,askip)
This SFE order replaces the simple SF order (x'1DF0') that we
had previously, which means that our stream becomes:
x'114Ø4Ø1DFØ114D7429Ø242F6CØF8'===>x'1D4Ø13114E581DFØ'(Enter your name)
If we also want our arrow in reverse video, then we add another
byte pair – hilight (X'41') with the desired value x'F2' – and our
SFE, now with three byte pairs, becomes
X'290342F641F2C0F8'. The sequence in which the byte pairs
are specified is not important, as long as they correspond to the
total number indicated.
The last type of attribute mentioned above – the outline – is
probably less known and less used than the others. Indeed, I
only discovered it quite recently, and not all 3270 emulators can
display outline.
Field outlining consists of drawing a thin line above, below, or
at the sides of a field, in any combination. The above and below
lines are drawn just in between the text rows, and don’t occupy
a character cell. The left line is drawn in the ‘dead’ byte (the
position just before a field, where the cursor never stops) that
precedes the field, and the right line goes into the next field’s
dead byte; both left and right lines occupy a character cell.
The field outline code is x'C2', and the value is a byte in which
the four left bits are zero and the four right bits each indicate a
line position, in any desired combination, so the byte can range
from x'00' (no outlining) to x'15' (full box).
If we wanted our example input field to be fully outlined, so that
it appeared with a box drawn all around it, we would start by
replacing the start field (SF) order with an SFE order. We would
then choose the byte pairs: the outline pair (x'C20F'), the
attribute pair (X'C040'), and perhaps also a colour pair, to avoid
the default colour. Let’s imagine, however, that in this case we
aren’t bothered about colour specification. Our SFE will be:
x'2902C20FC040', and our stream becomes:
x'114Ø4Ø1DFØ114D7429Ø242F6CØF8'===>x'29Ø2C2ØFCØ4Ø13114E581DFØ'(Enter
your name)
Note that outline should not be confused with underline (which
is part of the ‘hilight’ feature). An underlined field has a thicker
line than a lower outline. It’s also possible to have a field both
outlined and underlined, and the two lines will be clearly distinct.
Note also that the drop-down boxes of ISPF (and DITTO)
menus are not made with outlining (this is discussed in more
detail later).
The last order to discuss is the ‘set attribute’ (SA) order, which
modifies the characteristics of a field starting at the point where
it is inserted. To undo this modification and restore the field to
its previous characteristic, issue another SA order for the same
characteristic with the default value x'00'. It consists of three
bytes: the SA order code (x'28') followed by a single byte pair,
identical to the byte pairs used in SFE. An SA can be inserted
anywhere in a stream: after a set buffer address order, in the
middle of text, and so on. Unlike start field orders that take up
a ‘dead’ byte, SA orders don’t occupy the screen, so you can
assign a different colour to each letter of a word, or make it
appear as reverse, or blinking, etc. By the way, this is how the
ISPF editor creates those effects when you FIND text or when

you HILIGHT the syntax of a program source.
Let’s say that you want the last sentence of our example stream
to appear with the parentheses blinking, and a different colour
to each letter of the word ‘Enter’. The SAs to use would be
x'2841F1' (blink), x'284100' (undo the blink), and x'2842Fn' for
the colours, where n is the colour number.
That part of the stream would become:
x'2841F1'('2841ØØ 2842F4'E'2842F7'n'2842F1't'2842F3'e'2842F5'r your name
x'2841F1')
which reads: set blink, ‘(’, undo blink, set colour green, ‘E’, set
colour white, ‘n’, etc.
I suggest that you pause here and practise a little based on the
above examples, until you become familiar with the whole
process, starting simply and gradually increasing the degree of
complexity. The most common causes of error are malformed
addresses, incorrect values in byte pairs, incorrect number of
byte pairs specified in SFE, and so on.

https://www.cbttape.org/xephon/xephons/sna0212.pdf