Parameter name: &propertytype=
Property types may be specified with the &propertytype= parameter. This field accepts a comma separated list of property type names. When more than one MLS is searched, the property type names change to generic names rather than those names as customized by the MLS (e.g. “Single Family” may become “Residential” when more than one MLS is chosen). The list of generic names include Residential, MultiFamily, Land, Commercial, Farm, and Rental.
Example(Residential Property Type):