Warning, rant below:
I'm trying to learn how to work with XML in PL/SQL. So, I need some examples and reference manual. For C# or WINAPI I'm used to search for method names on google and usually I get link to MSDN. There is detailed explanation about method, parameters, types, usual and special values. There is often example of usage.
That's not true for Oracle documentation. Look at this . Procedure doesn't have it's own page, name of link is cryptic, so google has small chance. The documentation is poor, missing hyper-links to types of procedure parameters. This is documentation given by Oracle programmers, not by documentation writer.
There are zilions of users of Oracle database struggling with basics, just because of bad documentation. If you are searching for solution to your question, you usually find some discussion group with bad example of usage from some other confused user and below some non-authoritative response from people repeating same answers twenty times a day.
Another problem is that there is no documentation standard for in code documentation of PL/SQL. There are some open-source tools which are trying to map for example javadoc tags to procedures, but nobody knows about that.
I hope I missed something and someone will tell me where are standards described and who is evangelizing about it. Someone will give me link to real reference documentation to Oracle built-in packages.