Byte Alignment Rule

I dont know the 16 bytes thing before -_-!

in reference to:

"General Byte Alignment Rules The following byte padding rules will generally work with most 32 bit processor. You should consult your compiler and microprocessor manuals to see if you can relax any of these rules. Single byte numbers can be aligned at any address Two byte numbers should be aligned to a two byte boundary Four byte numbers should be aligned to a four byte boundary Structures between 1 and 4 bytes of data should be padded so that the total structure is 4 bytes. Structures between 5 and 8 bytes of data should be padded so that the total structure is 8 bytes. Structures between 9 and 16 bytes of data should be padded so that the total structure is 16 bytes. Structures greater than 16 bytes should be padded to 16 byte boundary."
- Byte Alignment and Ordering in Message Definition (view on Google Sidewiki)