+* `<TMPL_VAR ALBUM>` - page name of the album
+* `<TMPL_VAR ALBUMURL>` - relative URL to the album
+* `<TMPL_VAR ALBUMTITLE>` - title of the album, usually taken from
+ a [[ikiwiki/directive/meta]] directive
+* `<TMPL_VAR CAPTION>` - caption for the image
+* `<TMPL_VAR THUMBNAIL>` - a small [[ikiwiki/directive/img]] for the image
+* `<TMPL_VAR IMAGEWIDTH>` - width of the full-size image in pixels
+* `<TMPL_VAR IMAGEHEIGHT>` - height of the full-size image in pixels
+* `<TMPL_VAR IMAGEFILESIZE>` - size of the image, e.g. `1.2 MiB`
+* `<TMPL_VAR IMAGEFORMAT>` - format of the image, typically `JPEG`
+
+The template for the viewer page can also contain:
+
+* `<TMPL_VAR IMG>` - a large [[ikiwiki/directive/img]] to display the image
+* `<TMPL_VAR PREV>` - a link to the previous viewer, typically with a
+ thumbnail
+* `<TMPL_VAR NEXT>` - a link to the next viewer, typically with a
+ thumbnail