RDF/XML Syntax Question: Label on an RDF Object being a literal

I got a question on RDF/XML syntax.
I would like to put an rdfs:label on an RDF object being a literal.

In RDF I read that rdfs:label takes as input an rdfs:Resource
http://www.w3.org/TR/rdf-schema/#ch_label
and found that the literal (rdfs:Literal ) is a subclass an rdfs:Resource
http://www.w3.org/TR/rdf-schema/#ch_literal

Therefore it should be possible to do so.

Why do I like to do it? Imagine I got in ODF a table

<table:table-cell office:value-type="date" office:date-value="1980-09-02">
<text:p>2. September 1980</text:p>
</table:table-cell>

In above example there are two strings for the same date:
1) In the attribute there is the string the ODF implementation should
work with "1980-09-02"
2) In the paragraph within the cell is the human readable string "2.
September 1980" (the label)

Similar I desire an adequate solution for RDFa, where

<table:table-cell
xhtml:about="uri:subject"
xhtml:property="uri:property"
xhtml:content="1980-09-02"
office:value-type="date" office:date-value="1980-09-02">
<text:p>2. September 1980</text:p>
</table:table-cell>

The description for the RDFa you find here:
http://docs.oasis-open.org/office/v1.2/part1/cd04/OpenDocument-v1.2-part1-cd04.html#attribute-xhtml_about
"If an xhtml:content attribute is present, the above mentioned literal
content becomes a label."

Thanks for any help,
Svante