🚀 go-pugleaf

In article <86010005@hpcndaw.CND.HP.COM>, mds@hpcndaw.CND.HP.COM (Mark Smith) writes:

> Whoops. Ignore my previous posting. I misunderstood what you were trying 
> to accomplish. You want a string which is limited to "A" or "B" characters
> AND is restricted to a size of 10 characters.
> 
> Therefore, you would need to specify it as:
> 
> Str1 ::= IA5String (FROM("A"|"B")) (SIZE(10))
> 
> 
> Sorry for the confusion,


The confusion is caused by one problem -- the lack of an AND operator in the
language. I mentioned in a previous posting that the construction:

	  IA5String (FROM("A"|"B")) (SIZE(10))

was "incorrect". Well, nonbody is perfect. I was wrong. If one reads carefully
the BNF of ASN.1, one finds that:

    <type> ::= <type-declaration> |
	       <type> <subtype-declaration>

which means that one can list a string of space separated subtype
declarations. This BNF construct, however, is not explicited in the ASN.1 text
itself -- which let me wrongly conclude, following the text, that only one
subtype should be allowed.

May I suggest that we introduce an explicit AND operator in the constraint
notation? After all, are we absolutely sure that we will never have to enter a
constraint like:

	   IA5String (((FROM("A"|"B"))&(SIZE(10))|
		      ((FROM("C"|"D"))&(SIZE(20))))

Christian Huitema