Working with Variables and Expressions 16 The function used here is UCase(), which converts a string into all uppercase characters. The argument is the string "hello". The function does its work, and the assignment statement stores the string "HELLO" into the local variable Convert. NOTE #s can sometimes be confusing when you're using functions with ColdFusion variables. The proper way to use #s with a function and variable is as follows: #DateFormat(SellDate)# not: #DateFormat(#SellDate#)# Nested Functions Functions can also be nested. This means the argument of a function can be another function itself. A very common example of nesting is using the DateFormat() function with the Now() function, as follows: DateFormat(Now()) Functions with Masks Some functions also have another option called a mask . Functions that do formatting often have masks so that they can be tailored to an individual developer's needs. Again, consider the Date- Format() function. Say you want to change the default format to a date in the form mm/dd/yy.