Answer: Topic names and topic filters are used in their literal form. Add "Topic level separators may appear adjacent in a Topic Filter or Topic Name to indicate a zero length topic level" as follows: Change Section 4.5.1.1 (WD 12) Lines 1298 - 1301 The forward slash ('/' 0x2F) is used to separate each level within a topic tree and provide a hierarchical structure to the topic names. The use of the topic level separator is significant when either of the two wildcard characters are encountered in topic filters specified by subscribing Clients. Topic level separators may appear anywhere in a Topic Filter or Topic Name. Adjacent Topic level separators indicate a zero length topic level. Topic names and topic filters are used in their literal form.