Working with character sets

A character set, sets available all the possible characters that could be potentially used for a specific character in a pattern. That being said you can specify that you accept one character in your pattern to hold letters between E and K. You can do that by typing [E-K].

Same applies to numbers also as you can see with the picture above. 

Characters sets can also be combined. For example:

[0-5P-Q] => this matches a characters if it is a number between 0 and 5 (both included), or a letter between P and Q.

Bear in mind that a character set represents only one character in your pattern! If you want this pattern to expand to many characters read further!