MUST - This word, or the terms "REQUIRED" or "SHALL", mean that the definition is an absolute requirement of the specification.
SHOULD - This word, or the adjective "RECOMMENDED", mean that there may exist valid reasons in particular circumstances to ignore a particular item, but the full implications must be understood and
carefully weighed before choosing a different course.
"Data must be machine-readable and should be provided in bulk where possible."
"where possible" seems redundant.
"Data must be machine-readable and should be provided in bulk." seems equivalent.
From http://www.ietf.org/rfc/rfc2119.txt