A screen description matches the currently displayed application
screen if all of the descriptors contained in the screen
description are true.
The
host editor uses the following procedure to determine whether a particular
screen description matches the currently displayed application screen:
The host editor begins evaluating each descriptor in the screen
description, starting with the first descriptor and working through
sequentially towards the last descriptor.
For each individual descriptor that the host editor evaluates:
- First the host editor determines whether the descriptor, based
on its type and on the values of the properties it contains, is true
or false with respect to the currently displayed application screen.
For example, if the descriptor is a String descriptor and states that
the application screen has the text string "OPERATOR INSTRUCTIONS"
at row 1, column 11, and if in fact the application screen does have
that text string at that location, then the host editor determines
that the descriptor is true. Otherwise, the host editor determines
that the descriptor is false. (See Working with screen descriptors.)
- Then the host editor checks the Invert Match property of the descriptor.
If the Invert Match property is set to true, then the service flow
inverts the Boolean result obtained in the previous step, converting
true to false or false to true.
- If the Boolean result that the host editor has obtained at this
point is false, then the host editor immediately stops evaluating
the descriptors of this screen description and deems that this screen
description does not match the currently displayed application screen.
If the host editor finally evaluates all the descriptors contained
in the screen description and obtains a result of true for each one,
then the host editor deems that the screen description does match
the currently displayed application screen.