A decimal 13 is a hex 0D (base 10 versus base 16 numbers).
is it a standard form or can we use any other variables and can pass any value to the variable ?...
Transferring files requires a standard converntion be used between file creation and file usage.
The code must create the file in the format the "other end" is expecting.
CR/LF is rather common so i would not time investigating other values. And if what you have works, i would surely not change it without some business reason to do so.