#+LABEL: tab:xrf
is correctly and usefully exported to LaTeX as:
\label{tab:xrf}
A link in the org-mode file like this:
[[tab:xrf][(table 2)]]
behaves as expected in the pdf file compiled from the LaTeX export. In situations where it is not difficult to live without LaTeX's cross-referencing facility, this is great. (I know that it is possible to put \ref{tab:xrf} in the org-mode file and that this works beautifully in the LaTeX export, but it does nothing in the HTML export.)
The #+LABEL: tab:xrf doesn't appear in HTML export from the same org-mode file. If it could appear there, perhaps like this:
<a name="tab:xrf" id="tab:xrf"></a>
then one org-mode file would correctly export these cross-references to both LaTeX and HTML.
All the best,
Tom