Hi,

 initialize:function() works like constructor in the class.

private function=> _getDetails():function(){} consider as a private function as it starts with _

This is servicenow convention.

Client callable is basically checked on when you want your Script include works like a Async Call that means if you want your SI will return data to a UI form make it client callable otherwise not required.

Like if I call a script include in reference qualifier it is not needed to mark as client callable as we access it via className.functionName

but if it returns data & we want to set the data on the fields we have to make it client callable so that it can be called by the client side via GLIDEAJAX API.

Thanks

Sudhanshu