Minimum version: Midgard 1.4 (Bifrost)
This method has three 'modes' of operation.
When called with (domain, name), the value of the parameter will be returned.
When called with (domain, name, value) and 'value' being a nonempty string, the parameter denoted by (domain, name) will be set to 'value'. The parameter will be created if it doesn't exist yet.
When called with (domain, name, value) and 'value being an empty string, the parameter denoted by (domain, name) will be deleted.
Returns value of parameter or true if successfull. Returns false on failure.
Method available for: article, attachment, element, event, event_member, group, host, member, page, pageelement, pagelink, person, preference, sitegroup, snippet, snippetdir, style and topic records.