is it valid to use only digits as URI fragment identifier?

Is a li开发者_运维技巧nk like this valid?

http://some.server/some/path#123

According to "List of valid characters for the fragment identifier in an URL?" answers, it should be valid. However, APT parser complains that this kind of link is not valid.

These links are generated by JXR and I wonder if JXR should be fixed or is APT parser broken (APT is used by Maven site plugin).

That link is invalid for html/xml documents. Fragment identifiers refer to id or name attributes of tags.

ID and NAME tokens must begin with a letter ([A-Za-z]) and may be followed by any number of letters, digits ([0-9]), hyphens ("-"), underscores ("_"), colons (":"), and periods (".").

http://www.w3.org/TR/html4/types.html#type-name

For what it's worth. I have noticed this years ago and filed a bug: http://jira.codehaus.org/browse/JXR-87 Ridiculously, this is a one line to fix.