%local
$global
object
all objects are global if you refer to them from ID's (%object.getID()) or their names (%object.getName())
ClientGroup is just a named object, some functions like .getDatablock() refer to the IDs
For efficiency:
You don't want to use %object.getDatablock() == MyData.getID(), but instead use %object.getDatablock() == nameToID("MyData");
Also, strings that aren't objects default to 0, so when you want to compare strings, use $=