in command-line-debugger/src/main/java/org/apache/tools/ant/listener/DebuggerListener.java [210:215]
public void printUsage(Project project) {
project.log("Usage: break property some.property.1 some.property.2");
project.log(" break target some.target.1 some.target.2");
project
.log("The above command will add all properties/targets as breakpoints.");
}