In the Python 3.3.2 documentation in the section "6.2.1. Regular Expression Syntax" subsection "(?aiLmsux)" it describes flags that are set by extention notation. 6 of the flags are described in detail with links for each flag, but the "u" flag is not described or linked to in this subsection. 

When reading this subsection, you may be confused as to what the "u" flag is for, or if it even belongs there, since there is no link. I suggest that a link be added in that subsection to the re.A section in 6.2.2, and that re.U be added as a title for the re.A subsection in 6.2.2.