To create a category of the form "YYY0s in sport", where YYY0s is a 4-digit decade and sport is a sport.
e.g. Category:1910s in ice hockey
Usage
{{YYY0s in sport category header}}
Optional:
{{{parentsport}}}
and {{{parentsport2}}}
to categorize this sport under other sports.
e.g. {{YYY0s in sport category header|parentsport=winter sports|parentsport2=hockey}}