Template:Categories
Do not transclude this in PD help pages (Help namespace), since it seem to break the PD help guidelines, in that, this template name is not suitable to be included in a fresh wiki installation. For PD help pages, use Template:Help/Categories instead.
Example
{{#ifeq: categories|Categories || }}
{{#if: | {{#ifeq: categories|Categories |{{#ifexist: {{{1}}}/categories |{{ {{{1}}}/categories|En pagename=Categories|Lang subpage=}}}}|{{#ifexist: {{{1}}}/categories |{{ {{{1}}}/categories|En pagename=Categories|Lang subpage=/Categories}}}} }}{{#if: |{{#ifexist: {{{1}}}/categories |{{ {{{1}}}/categories }}}}}} | {{#ifeq: categories|Categories |{{#ifexist: Template:Categories/categories |Template:Categories/categories}}|{{#ifexist: Template:Categories/categories |Template:Categories/categories}} }}{{#if: |{{#ifexist: Template:Template:En pagename/categories |{{ Template:Template:En pagename/categories }}}}}} }}