But you can always use negative kerning and baseline shift to get any two characters to overprint each other at any desired horizontal and/or vertical offset.
Could you copy the text from help system here in forum?
Are those "mathematical symbols" part of the Symbols font? What about getting a maths-specific symbol font which includes what you need? Go here and see what's available: <http://www.myfonts.com>
If you do a Show Options on the Character palette so that the less frequently used options show, the bottom item looks like an A with a superscripted a. This is the "Baseline Shift" attribute. (If you hold the mouse over the icon it shows the name of the item.) The Baseline Shift units are in points or whatever units you are using for Font Size, so if you change your font size you will need to change the baseline shift.