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It is my opinion that the size constraint in
this case must be respected; otherwise, it has no meaning. Clearly, the
person who wrote this definition wanted the bit string to be between 15 and 32
bits in length, otherwise the size constraint would not have been added.
As to precise language in the standards stating this, I could not find
any.
Regards,
----- Original Message -----
Sent: Friday, February 28, 2003 4:27
AM
Subject: [ASN.1] Question on BER
Dear ASN.1
experts
In order to solve an
interoperability problem resulting from different interpretations of ITU-T
X.690, your help on the following question is very much
appreciated:
A BER encoded message contains a
data type for which the abstract syntax is defined as
DataType ::= BIT STRING
{
bitOne
(0),
bitTwo
(1),
bitThree
(2),
bitSeven
(6),
bitEight
(7),
bitNine
(8),
bitFour
(3),
bitFive
(4),
bitSix
(5),
bitTen
(9),
bitEleven
(10),
bitTwelve
(11),
bitThirteen
(12),
bitFourteen
(13),
bitFifteen
(14),
bitNineteen
(18),
bitTwenty
(19),
bitTwentyone
(20),
bitTwentytwo
(21),
bitTwentythree
(22),
bitTwentyfour
(23),
bitTwentyfive
(24),
bitTwentysix
(25),
bitTwentyseven
(26),
bitTwentyeight
(27),
bitTwentynine (28)}
(SIZE (15..32))
The entity sending the message
encodes this data type as:
03 TAG
02 length
00 no unused
bits
80 bitOne set to 1, bitTwo to
bitSeven set to 0
The entity receiving the message
does not accept it due to the SIZE constraint not being respected and performs
the appropriate error handling.
Now designers of the sending
entity argue that ITU-T X.690 � 8.6.2.4 and � 11.2.2 allow the encoder to
encode the data type as shown above whereas designers of the receiving entity
do not share this view and insist on the SIZE constraint being
respected.
Dear Experts,
please let me know which of the
above interpretations of ITU-T X.690 is correct and whether or not X.690 is
incompatible to X.209 in this respect.
Thank you in
advance
Ulrich Wiehe
GKS
AG
Gesellschaft f�r
Kommunikations
Software Tel:+496621
169139
MMC2
Fax:+49 6621 169 122
Breitenstr.
57
Mobil: +49 151 14016088
D-36251 Bad
Hersfeld
e-mail: [EMAIL PROTECTED]
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