INCLUDINGWEB -- web that includes current topic

The web name of the topic that includes the current topic - same as %WEB% if there is no INCLUDE. If a topic is used in a chain of INCLUDEs, INCLUDINGWEB is set to the topic directly INCLUDing this one, NOT the web that has been requested by the user (which is given by BASEWEB)
ALERT! Be careful of the subtle difference between INCLUDINGWEB and BASEWEB. You probably should be using BASEWEB

BASEWEB, INCLUDINGTOPIC, INCLUDE, WEB