Hello Frank,

I'm writting a Perl RPSL parser module and have a understanding problem with part 2 "RPSL Names, Reserved Words, and Representation" page 5 of RFC 2622 ;-(

Good luck to you :)

"A value of an attribute may also be a list of one of these types. A list is represented by separating the list members by commas ",". For example, "AS1, AS2, AS3, AS4" is a list of AS numbers. Note that being list valued and being multiple valued are orthogonal. A multiple valued attribute has more than one value, each of which may or may not be a list. On the other hand a single valued attribute may have a list value."

Ok, a multiple attribute value can be a single value or a 'comma list' of values. But the last sentence confused me - "a single valued attribute may have a list value" ?

Means that "aut-num: AS123, AS456, ..." is a correct attribute of an aut-num object ?!?!

First let me define 'list value' and 'multiple/single valued' attributed. 'List value' refers to the attribute value (ie, can you have a list of values seperated by a comma as the attribute value). 'multiple/single valued' attributes specify if the attribute can appear in the object more than once. For example, the 'import' and 'export' attributes can appear more than once in the aut-num object, so 'import' and 'export' are multiple valued attributes. 'aut-num' can only appear once in the 'aut-num' class/object so it is single valued. 'mnt-by' is an example of a list valued attribute since you can specify a list of maintainers seperated by a comma.

Means that "aut-num: AS123, AS456, ..." is a correct attribute of an aut-num object ?!?!

No, since 'aut-num' is not defined as list valued. The aut-num attribute is also defined as single valued (so it cannot appear more than once in the object). Hope this helps. --jerry