The "-c" templates are designed to enable cells to be filled in with a yes, no or unknown, with a tooltip note.

These include:

Used in a table like this:

{| class=wikitable
!Heading One
!Heading Two
!Heading Three
|-
|{{Yes-c|c=Data is complete}}
|{{No-c|c=Data is incomplete}}
|{{Unknown-c|c=Unknown whether data is complete}}
|}

Creates:

Heading One Heading Two Heading Three
Yes No Unknown