+===== optQuarkAbsolute()/optQuarkRelative() =====
+
+These two methods are similar to their counterparts getQuarkAbsolute() and
+getQuarkRelative(). The only difference is that if the referenced attribute does
+not exist, the value ITmfStateSystem#INVALID_ATTRIBUTE (-2) is returned instead
+of throwing an exception.
+
+These methods should be used when the presence of the referenced attribute is
+known to be optional, to avoid the performance cost of generating exceptions.
+
+===== getQuarks() =====
+
+This method (with or without a starting node quark) takes an attribute path
+array which may contain wildcard "*" or parent ".." elements, and returns the
+list of matching attribute quarks. If no matching attribute is found, an empty
+list is returned.
+