10. The key-symbol dictionary according to claim 9 , wherein: the bridge corresponds to two letters of the single keyword; the source is associated with the two letters of the bridge in upper case, the source including at least three variations: a first letter in upper case and a second letter in lower case; the first letter in lower case and the second letter in lower case; and the first letter in lower case and the second letter in upper case; and the three variations of the source are associated with a respective one of the three icons.
10. The key-symbol dictionary according to claim 9 , wherein: the bridge corresponds to two letters of the single keyword; the source is associated with the two letters of the bridge in upper case, the source including at least three variations: a first letter in upper case and a second letter in lower case; the first letter in lower case and the second letter in lower case; and the first letter in lower case and the second letter in upper case; and the three variations of the source are associated with a respective one of the three icons. 11. The key-symbol dictionary according to claim 10 , wherein the source and the three icons associated with the source are presented in a four-part matrix, each of the four parts corresponding to one of the source and the three variations.