To obtain a list of attribute types you can use the 'attributetypes' call. You can't use this data directly for searching but you can use it to obtain a list of attributes to use in a search. For example you may want to have an 'Experience' drop down with options such as 'Wildlife' and 'Food and Wine'. This call allows you to discover the list of possible attribute types.
Results can be request in JSON or XML format.
To obtain results in a different market variant you can use the 'mv' parameter.
A list of categories to retrieve the classifications for.