 a blob represents a sequence of octets.</p><p>Scheme systems implementing both SRFI 4 and/or SRFI 66 and this SRFI may or may not use the same type for u8vector and blobs.  They are encouraged to do so, however.</p><p>As with u8vectors, the length of a blob is the number of octets it contains.  This number is fixed.  A valid index into a blob  is an exact, non-negative integer.  The first octet of a blob  has index 0, the last octet has an index one less than the  length of the blob.</p><p>Generally, the a