DuckCorp Dico

Found one definition

1.                 From The Jargon File (version 4.4.7, 29 Dec 2003):
                   
   
   
                   
                     
   loose bytes
    n.
       Commonwealth hackish term for the padding bytes or shims many compilers
       insert between members of a record or structure to cope with alignment
       requirements imposed by the machine architecture.