Existing stations apply for permits and license amendments when making changes to their facilities (such as relocation to another site, changing the radio antenna height, making changes to a directional antenna's radiation pattern, or when adding—or converting to—digital broadcasting). Other situations (such as a change in the city of license) are covered in rulemaking proceedings in the U.S., which may be a prerequisite to moving a station a significant distance (leaving its original community outside its new coverage area). Temporary situations are covered by special temporary authority (STA) to operate at a variance from the license or permit or a Restricted Service Licence (RSL) to operate for a fixed period at reduced power. While these are FCC and Ofcom terms, respectively, other countries have similar regulations.