Re: [ASN1] a quesion on Permitted Alphabet constraint

[WangHao]

According to 47.7.3, the sub-alphabet includes precisely those characters which appear in one or more of the values of parent string type which are allowed by the "contraint".   Now, in my 4) example, parent strint type is IA5String, "contraint" is SIZE(4), so, the sub-alphabet is the characters from the strings of parent string type with its length constrained to 4. Since the strings of length 4 in parent string type may includes all the characters of IA5String, the sub-alphabet is as same as the IA5String. In my opition, the permitted alphabet in the 4) may contrain nothing on the parent type. Is it right?   So, does anyone make it clear what the exact semantics of permitted alphabet is when the "contraint" in the PermittedAlphabet is contained subtype, size constraint or pattern constraint?    I think that my analysis about the equivalence is right except size constraint case which should not affect the characters in the sub-alphabet from the parent type.    Author Name: Wang Hao Phone:+86-755-89650628 EMail:[EMAIL PROTECTED] ***************************************************************** This e-mail and its attachments contain confidential information from HUAWEI, which is intended only for the person or entity whose address is listed above. Any use of the information contained herein in any way (including, but not limited to, total or partial disclosure, reproduction, or dissemination) by persons other than the intended recipient(s) is prohibited. If you receive this e-mail in error, please notify the sender by phone or email immediately and delete it! ***************************************************************** ----- Original Message ----- From: Salim Alaoui To: WangHao ; [EMAIL PROTECTED] Sent: Thursday, October 28, 2004 5:33 PM Subject: Re: [ASN1] a quesion on Permitted Alphabet constraint >>For example, 4) is equivalent to the notation DummyString4 ::= IA5String(SIZE(4)). FROM(SIZE(4)) in my opinion is that the maximum size is 4 which is not quite equivalent to (SIZE(4)) where the size has to be exactly 4.   -Cheers-   Salim Mounir Alaoui, Ph.D. WangHao <[EMAIL PROTECTED]> wrote: Hi,   The clause 47.7.1 of X.680 says _________________________________________________________________________________ The "PermittedAlphabet" notation shall be      PermittedAlphabet ::= FROM Constraint. ________________________________________________________________________________   The clause 47.7.3 of X.680 specifies ________________________________________________________________________________ The "Constraint" is any which could be applied to the parent type (Table 9), except that it shall use the "SubtypeConstraint" alternative of "ConstraintSpec". ________________________________________________________________________________   So, the following forms of permitted alphabet constraints are all valid according to 47.7.3:   1)DummyString1 ::= IA5String (FROM("A".."B")) -- value range form   2)DummyString2 ::= IA5String (FROM("A"))  -- single value form   3)DummyString3 ::= IA5String (FROM(INCLUDES DummyStringType))     -- contained type form     DummyStringType ::= IA5String (FROM("abcd"))(SIZE(4))   4)DummyString4 ::= IA5String (FROM(SIZE(4))) -- size constraint form   5)DummyString5 ::= IA5String (FROM(PATTERN "[a-z]+"))   However, as this subtype element implies, permitted alphabet selects the charaters which are allowed to be used to construct strings of the new constrained type. So, I think that only 1) and 2) make sense. 3),4) and 5) are equivalent to the contraints within the PermittedAlphabet notation.   For example, 4) is equivalent to the notation DummyString4 ::= IA5String(SIZE(4)).   So, my question is why not change the clause 47.7.3 of X.680 into the following statement:  "The 'contraint' is only limited to the single value, the contained subtype and the value range   or set arithmetic of them" ?         Author Name: Wang Hao Phone:+86-755-89650628 EMail:[EMAIL PROTECTED] ***************************************************************** This e-mail and its attachments contain confidential information from HUAWEI, which is intended only for the person or entity whose address is listed above. Any use of the information contained herein in any way (including, but not limited to, total or partial disclosure, reproduction, or dissemination) by persons other than the intended recipient(s) is prohibited. If you receive this e-mail in error, please notify the sender by phone or email immediately and delete it! ***************************************************************** _______________________________________________ ASN1 mailing list [EMAIL PROTECTED] http://lists.asn1.org/mailman/listinfo/asn1

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