[OAI-implementers] Superscript- and subscript-nodes

[Thomas G. Habing]

Dr. Elmar Haake wrote:
> Hi,
> 
> Since we are acting as an OAI-Data- and OAI-Service-Provider we are
> interested in implementing special characters in our repository.
> We guess that it must be possible to implement UTF-8-coded numeric
> entities in the OAI2.0-interface. But how is it with superscripted
> characters like <sup>2+</sup>?
> These characters does not have numeric entities, so I would like to ask
> you about this case.
> 
> We think, it must be possible to output the node in the way like HTML
> (e.g. <sup>2%2B</sup>), because the service-provider could parse them
> via XSLT-processor in an own routine.
> But the characters "<" and ">" are not URI-encoded, so it would not be
> possible to transfer them via the OAI-interface in the described way. If
> we encode them, the XSLT-Processor cannot parse it to the HTML-node
> (parsing is only possible with nodes beginning with <....>, not with
> &lt;...&gt;)
> So we resides in a dilemma. As a possible solution we think about
> cutting them away. But on this way we would modify the content which is
> not optimal for exchanging the metadata.
> 
> Has someone of you any experiences or ideas?
> 
> Greetings
> Elmar
> 

There are Unicode code points for various superscripted and subscripted 
characters in the ranges U+2070..U+209F plus U+00B2, U+00B3, and U+00B9. 
  Because of font issues, most systems cannot display more than just the 
numbers 1-3 as superscripts, but it might be adequate for your needs, 
for example, <sup>2+</sup> could be encoded as &#xB2;&#x207A;

If you need to represent more complex math in Unicode you might want to 
check out the technical report "Unicode Support for Mathematics" at 
http://www.unicode.org/reports/tr25/index.html and also