In a museum exhibition it is wise to allow a maintenance passage or alleyway all round the perimeter of the site. Overhead access can be given but it is frequently difficult, as with front access, to carry out essential maintenance during the open hours of the exhibition or museum. Security can present a problem for maintenance if there are valuable exhibits which also need proximate attention to equipment. Another aspect of maintenance applies to equipment used to make life in an exhibition more bearable. Maintenance therefore is a job for professionals. When changes of staff are necessitated for temporary or permanent exhibitions, it is important that the new staff should be fully briefed with regard to maintenance. To this end it is useful to have maintenance schedules and documents which are regularly updated for every contingency. The final aspect of maintenance is simple cleaning.