Template:Tsubst tsd
{{subst:subst}}tsubst tsd|{{subst:tsd|{{{1}}}}}
Demo for producing a substitution demo. In this case it shows the result of substituting Template:Tsd for a particular set of parameters. After a change in that template it just requires pressing edit and save on the page Template:Tsubst tsd/doc to update the substitution demo.
{{subst:tsd|abc}} gives "
start - abc - end ".- Substituting this template produces one or more new substitution template calls, allowing recursive change of a page, see Help:Recursive conversion of wikitext.