COOSYSTEM@1.1:attrfilterexpr

Expression that either determines or filters the possible selection of objects in an object pointer control. If used in conjunction with AttrFilterCheckSet this expression is used to test the value of a property (of any type).
This expression is examined before execution. If the expression returns OBJECT or OBJECTLIST the scopes are set as defined in attrfilterobjectexpr.

• ::this (global scope) ... list of objects that should be filtered. If ::this is empty, the expression should retrieve a meaningful default for objects that are usable as a value for the property. If in that case the expression terminates with the error COOSTERR_BREAK, the default list of values derived from the property usrenvlocalobjects is used.
• this (local scope) ... object containing the property.
• Use attrfilterobjectexpr to validate the expression

Otherwise the expression must return BOOLEAN. In this case the following values are used for the scopes:

• ::this (global scope) ... object containing the property.
• this (local scope) ... object that is checked.
• Use attrfilterbooleanexpr to validate the expression

Explanation:
Defines an app.ducx expression that specifies the selectable values of the property (see also attrfilterexpr).