Template:Category pair

Usage
Place on the top of the category page, replacing " " with the names only of the target categories, leaving out the term " ".

Each category is displayed only if it exists. If neither category exists, nothing will be displayed.

If there is no succeeding category, you may simply place: on the top of the category page, replacing " " with the name only of the target category, leaving out the term " ".

If there is no preceding category, then leave the first parameter empty, and simply place: on the top of the category page, replacing " " with the name only of the target category, leaving out the term " ".

Examples

 * Preceding and succeeding categories, both exist
 * Preceding category only, which exists
 * Succeding category only, which exists
 * Preceding and succeeding categories, only preceding exists
 * Preceding and succeeding categories, only succeeding exists
 * Two non-existent categories, so no output:
 * Preceding and succeeding categories, only preceding exists
 * Preceding and succeeding categories, only succeeding exists
 * Two non-existent categories, so no output:
 * Preceding and succeeding categories, only succeeding exists
 * Two non-existent categories, so no output:
 * Two non-existent categories, so no output:

Error checking
If more than two parameters are supplied, a warning message is shown when the page is previewed and when it is saved the page is added to a hidden tracking category: Category:Pages using Template:Category pair with more than 2 parameters.

Only the first two parameters are processed. Others are ignored.

If more than two parameters are supplied, the template is unlikely to do what the editor intended e.g.
 * will ignore CATEGORY NAME3
 * will ignore CATEGORY NAME2, because a duplicate  character between the two categories causes CATEGORY NAME2 to be the third parameter rather the second

Tracking categories

 * Category:Pages using Template:Category pair with no output
 * If neither parameter is a category which currently exists the template will produce no output. This is not necessarily an error; the other categories may simply be part of an incomplete series which will be completed in due course


 * Category:Pages using Template:Category pair with more than 2 parameters
 * See above: Error checking