regex search for one or more instances of a character set

When you add a plus sign '+' after characters identified within square brackets in a regular expression search, the search will find any instances where one or more of these characters appear. So this search:

[A-D]+[0-5]+[a-c]+

. . . will find strings which begin with one or more instances of the uppercase letters between A to D, one or more digits between 1 and 5, and end with one or more of the lowercase letters between a and c.