Many users find that when typing characters or selecting templates in MathType or the Equation Editor, inappropriate characters are displayed. There are many types of font encodings. Text fonts, such as Times New Roman, have an ANSI encoding that contains Roman letters, Arabic numerals, punctuation marks, and other special text symbols. Arial, Courier, Garamond, New York, Palatino are some other fonts that have standard ANSI encodings, as is the Euclid font included with MathType 4.0 for Windows. The fonts that you would use in an email or word processing document have ANSI encodings.
Symbolic fonts have other characters.
The Symbol font, for example, has Greek letters, mathematical operators and symbols, and characters which are used to construct large integrals, parentheses, braces, and brackets. The Symbol font does not include Roman letters. The MT Extra font, which is included with MathType and the Equation Editor, includes additional characters which are not present in the Symbol font or fonts with ANSI encodings. If a font with an inappropriate encoding is assigned to one of the Styles for MathType or Equation Editor, the result will be equations with inappropriately substituted characters. MathType 4.0 for Windows users should not experience this problem because MathType 4.0 is aware of the encodings that fonts use and will not allow a font lacking the necessary characters to be assigned to one of its Styles.