A SEQUENCE containing empty OPTIONAL elements is encoded as a SEQUENCE
of zero
length.
Yes, no doubt.
An empty SEQUENCE which is an OPTIONAL element is absent in the
encoding.
I would be happy with the interpretation that an empty SEQUENCE which is
OPTIONAL
as a whole MUST be absent in the encoding. But ISO 8825 clause 15 about the
encoding
of <SEQUENCE OF> values gives me evidence that encoding this as a SEQUENCE
of zero
length would be in line with 8825, too. Can you provide me the conclusion why
it MUST be absent?
X.209 clause 15.2 refers to the content octets of the SEQUENCE. The SEQUENCE
tag and
length still get encoded. This is the "SEQUENCE containing empty OPTIONAL
elements".
See X.208 clause 20.4 Note 2
See also X.208 clause 36.6.9, and subparagraphs.
Wolfgang
John