Keep this sandbox. It is linked to from here:
All of these work on both the Commons and Wikipedia:
This category does not exist on either the Commons or Wikipedia:
--- Some tests of Template:See also. With and without a colon in front of category ---
{{See also|:Category:Abc|:Category:Data|Category:Test|Commons}}
Removing the colon in front:
{{See also|Category:Abc|Category:Data|Category:Test|Commons}}