====== Page ids, namespaces, relative ids ====== ===== Page ids ===== A page id uniquely identifies the page within your wiki. Page ids may contain only characters ''%%[a-z]%%'', numbers ''%%[0-9]%%'', hyphens ''-'' or underscores ''_''. Page ids may not start with a hyphen. Page ids are case-insensitive. ===== Namespaces ===== Namespaces are a convenient way to organize your pages by grouping them . The namespace is the name of such a group. Namespaces follow the same rules as page ids: * they may only contain alphanumerical characters, hyphens and underscores * they may not start with a hyphen * they are case-insensitive Namespaces can be nested, i.e. you can have sub-groups of pages within a group of pages. Page ids must be unique within their closest containing namespace. In other words, you can have 2 pages with the same id, provided that they belong to different namespaces. ===== Full page ids ===== A page's **full id** refers to the combination of namespaces and page id, separated by a colon. This string provides a unique identifier for any given page. Nested namespaces must be listed in order. For example, the full id ''page:ids'' refers to the page id ''ids'' in the namespace called ''page''. The full id ''ns1:ns2:start'' refers to the page with id ''start'' contained in the namespace ''ns2'', itself contained inside the namespace ''ns1''. ===== Relative page ids =====