XML Standard for Real Estate property

Is there a standard XML format for property listings?

I've found a couple:

• reaxml1 reaxml.realestate.com.au/docs/reaxml1-xml-format.html
• RELML www.xml.com/98/08/real/relml-dtd.html

but which is best / most used? Has anyone created xml property listings using these?

In Australia at least, the "de facto" standard is REAXML. Easily the most used real estate XML specification in that country. In my work I've created both importers and exporters of REAXML data. In South Africa I know of at least one web dev firm that accepts REAXML (for remax.com.au)