Re: Cursor Position

[Douglas Handy <dhandy1@xxxxxxxxxxxxx>]

Jim,

>Apparently back in the days of the S36 it
>was much faster to just set on one indicator and ignore the others than
>to set all the indicators.

This has nothing to do with it.  On the S/36 there was no means to differentiate
between CAxx and CFxx keys in $SFGR.  It was introduced on the S/38 (which
predates the S/36) mostly because of the validation options available under DDS,
and these didn't exist in $SFGR either.  The closest thing in $SFGR was an
option at the record format level to not return data if the master MDT bit was
not set on.  But this applied to Enter as well as all Cmd keys.  It was just a
way to cut down on traffic levels if no data was changed by the user.

It is easy to remember the difference in DDS when you know what they stand for:

 - CFxx = Command Function; the data is required for a function (eg F4 prompt)
 - CAxx = Command Attention; interrupt program flow and ignore the screen data

With CAxx, most DDS validations are ignored which allows the user to press
things like CA03 or CA12 regardless of screen contents.  There are few things
more frustrating to a user than having to enter valid data in a screen which
they are trying to have ignored anyway.

Typically I use CAxx for F3, F5, and F12 and CFxx for most others, but I always
base it on whether or not I will process the screen data.  If I won't, I use
CAxx; if I need the screen data I will use CFxx.  I do this partly as a matter
of principal since I loath DDS validations, but it does make a difference in
performance too, at least on low bandwith remote connections.  Why transmit what
will be discarded anyway?

Doug

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