Changing the attributes

Here is an example of how this works. Suppose that the terminals in our “quick check” application have color and highlighting capabilities. We might decide to show the maximum charge allowed in a different color from the rest of the screen, because this field is of most interest to the clerk. We might also make the warning message red, because when it appears at all, it is important for the clerk to notice it. And when we really want to get the clerk's attention, because the card is stolen, we could change the attributes in the program to make the message flash. To add these features, we need to change our map definition as follows:

QCKMAP DFHMDI SIZE=(24,80),..., X
MAPATTS=(COLOR,HILIGHT),COLOR=GREEN,HILIGHT=OFF,DSATTS=HILIGHT

The MAPATTS option tells BMS that we specify color and highlighting in the map (or in the program, because any attribute listed in DSATTS must be included in MAPATTS as well). The COLOR and HILIGHT values indicate that fields with no color assigned should be green and that highlighting should be off if not specified.

The only field definitions that we need to change are the ones that are not green or are highlighted:

CHG DFHMDF
POS=(5,13),LENGTH=8,ATTRB=(ASKIP,NORM),PICOUT='$,$$0.00', X
COLOR=NEUTRAL
MSG DFHMDF LENGTH=20,POS=(7,1),ATTRB=(ASKIP,NORM),COLOR=RED

Specifying COLOR=NEUTRAL means that on a terminal, the field is displayed in white.

The DSATTS option tells BMS that we want to alter the highlighting of some fields at execution time, and therefore it should produce “H”-suffix subfields in the symbolic map to let us do that. Each named field gets the additional subfield; the message field, for example, expands from the current three lines in Figure 3 to:

 02 FILLER PICTURE X(2).
02 MSGH PICTURE X.
02 MSGA PICTURE X.
02 MSGO PIC X(30).

The program statement we need to produce the flashing is:

 MOVE DFHBLINK to MSGH.

In general, BMS takes attribute values from the program if you supply them and from the map if you do not (that is, if you leave the program value null, as initialized). However, the MAPONLY and DATAONLY options on the SEND MAP command affect attribute values as well as field data, as explained in Where the values come from in Building the output screen.