a576ddfd_PHP__Runkit_Sandbox___Manual_x_Settings___Status_Indicators_Purpose
[Setting] parent_scope [Type] Integer [Default] 0 (Global) [Purpose] 
What scope will parental property access look at? 0 == Global scope, 1 == Calling scope, 2 == Scope preceding calling scope, 3 == The scope before that, etc..., etc...
PHP: Runkit_Sandbox - Manual
Purpose