To set the selection filter for the maintable in a form from a script or button. 

Selectionfilter is "Under-used" but very useful when one figure it out (which almost nobody have). It is deceptive in the fact it takes two arguments but that might be due to a wrong design that has been brought forward because the filter is simply a formatted string like you would use in DQL. 

You can put the entire filter in the first argument and leave the second one blank, but peculiarly not the other way around. 

You can use all operators in the filter like +>< between etc and you can even use functions like

CustomerNr=GetVar("CustomerNr") if you wanted.

As it will need a fully formatted string which would include "" if you compare a text field you will need to use the new StringEscape() functionality i.e. use /' for " in the string whcih will be converted to ".

You don't have to use StringEscape() function as it is built into SelectionFilter() and most other functions in DE8.

QueryPart1: Text

The first or whole selection criteria . Is necessary for the function not to give an error message. You can't call this with an empty filter.

QueryPart2: Text

This is optional, and you can simply put it blank i.e. "". There is no logical reason for using this.