Combining Diacritical Marks

The characters with numerical codes in the blocks 0x0300-0x036F and 0x20D0-0x20FF are combining marks. This means that rather than being displayed as characters by themselves they are attached to the previous character and (in most cases) displayed on top of it. For example, a vertical line (code 0x20D2) can be used after an equal sign (=). The result displayed is a negated equal sign: the vertical line is superimposed on the =.

These characters can be inserted from the Insert Symbol dialog (or from a palette present in the default toolbar file) but, because of their special nature, MathFlow handles them a little differently than the rest of the characters:

• Combining characters are only added to the data of an existing token element (an mi, mn, mo or mtext), and only after a regular character already in place.
• Once in place, the pair of normal and following combining characters are treated as a single character: it is impossible to step in between them, or insert new characters between them.
• When trying to delete a combining pair, either from the left (via delete) or from the right (via Backspace) the combining character is deleted first, leaving just the normal character.
• Only one combining character is allowed per normal character. If you attempt to insert more than one, all the ones after the first one are ignored.

See the Combining Diacritical Marks and Diacritical Marks for Symbols tables (in the Programmer Documentation section) for a list of characters.