Some Priority internals (SCREENMSG)

I had developed a form for a client and I wanted to document it. There are reports that purport to do this but they don't always give all the information, and my improved report doesn't exist on the client's computer. So I used the WINDBI Dump capability; one can dump a form and one can dump a form's cursor; the difference between the two is that the latter only gives the SQL query that populates the form whereas the former also gives triggers.

Looking at some of this information, my eye was caught by this statement:

SELECT 192 INTO :SCREENMSG

FROM DUMMY WHERE :RETVAL = 0;

I wondered what this could mean. Could it be that :SCREENMSG is a special variable in the same way that :ERRMSG is? Storing a number in :ERRMSG will cause the corresponding error message (from the procedure) to be displayed. So presumably the above statement will cause message 192 to be displayed on the screen. But where is 192 coming from? There were similar statements but with different numbers.

Maybe, I thought, there is a table called SCREENMSG or SCREENMSGS from which the value is automagically retrieved. And so it is: the table is SCREENMSG and value 192 is (translated into English), 'Value does not exist in the table'. I looked at all the values in the table and have to admit that I could not imagine any personal use for them.

At least another internal has been explained.