Application of codes is a common feature while solving Cryptic Clues in Crossword Puzzles as in Cryptic Clues Type "D"
In the process of solving them, some words are replaced by their respective codes before anagramming with a few other letters or words to derive the Answer word. Codes can be abbreviations, acronyms, symbols or just single letters that can mean or sound like a word. For example, the letter "A" can mean "one" or "single", letter "B" can mean "be" since they sound same (homophone), letter "C" can mean "see" - homophone again. Similarly letter S can mean "yes" but it can also mean "dollar" since S is the symbol for dollar. "L" can mean pound or fifty but can also mean "learner" or "left" and "R" can mean "right" or can mean "are". Likewise, X can mean "ten" (roman numeral) and Y can mean "why". More examples of codes are listed in the table below.
The list is by no means exhaustive and will be updated from time to time.