The thread on curly x reminded me of one notation used by both IB and Edexcel that really annoys me: using superscript * instead of a bar over the top. I imagine this harks back to the days when you needed to use Latex to print the proper notation. Using * is very clumsy and inelegant, so it's about time school text books did what universities have always done. At any rate, I encourage my students to use the proper notation. Another thing I've seen is the use of ]x,y[ instead of (x,y) for open limits. Is this another school foible, or is it a European abomination - like switching the use of the comma and decimal point?