Re: ipath-empty ABNF rule

* Markus Sabadello wrote:
>The ipath-empty rule in http://www.ietf.org/rfc/rfc3987.txt looks like this:
>
>ipath-empty       = 0<ipchar>
>
>I think this ABNF construct is called prose-val. I am wondering, can this be
>replaced with the following, with full preservation of the meaning?
>
>ipath-empty = ""

Yes. You can also replace it by `ipath-empty = 0ipchar`. Unfortunately
the ABNF specification allows to use <rulename> in the grammar, but does
not say that <rulename> always refers to the rule "rulename".

>The reason I am asking is that I am using the excellent Java aParse library
>(http://www.parse2.com/) to parse the IRI ABNF, but this library doesn't
>support prose-val (I've talked to the author of the library, he has been
>very helpful and explained that there seem to be ambiguous definitions as to
>what prose-val actually is).

Generally speaking, prose values are free form text, you could say e.g.
< a prime number > or < any string not matched by rule xy >. There is no
easy way for software to understand this free form text.
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