Hi,

I will try to break it but to answer in simple way $ANY looks like the answer.

$CLASS need to have some reference when you are using it in property that is used inside activity

When you select a property mode of Page, Page List, or Page Group. You can use such properties in activities to create embedded pages on the clipboard.

So either Identify a class for the value of the page property,

or enter one of the keywords described here.

Preferable select a concrete class.

Now

Suppose When you later configure an activity that uses this property, the activity cannot specify a different class for this property.

Note: The concrete class for the embedded page cannot differ from the class recorded here.

Now You can also  enter an abstract class or one of two keywords($ANY or $CLASS)

• $CLASS: if you use this

Benefits:

For more flexibility in activities that use this property, enter an abstract class or the keyword $CLASS

Two Things can happen here

1.  If you enter an abstract class, the activity at runtime must specify a concrete class derived from that abstract class

2. If you enter $CLASS, the activity must specify a concrete class (but it can be any concrete class). For example, the Code-Pega-List.pxResults property uses $CLASS.

• $ANY: If you use this

  Benefits:

  Enter $ANY to make the class of the page (or Page Group or Page List) assignable at runtime

So in $CLASS if it is used inside activity you must specify concrete class but if you use $ANY you can assign the class at runtime.

So from my understanding you can use $ANY for runtime.

Correct me if you find something else.

Also In the earlier versions, application used to have several activities that use $ANY in its Pages & Classes tab.

If the class is not determined/finalised at the time of writing an activity, developers used it as an easy way out.

Also Pega restricts the use of $Any/$Class/$NONE. So I haven't tried it myself .

Thank You