This template should be placed on the documentation subpage (not the template page itself) of any template that may be substituted (but may also be transcluded).
{{ifsubst}} – if-then-else metatemplate that checks if a template is currently being substituted or transcluded.
{{always substitute}} – For the doc of the above templates; prints a message asking for it be substituted.
{{frequently substituted}} – Notice displayed in the documentation of substitution templates notifying the user that the template is widely used.
{{never substitute}} – The reverse of {{always substitute}}. For the doc of templates which should not be substituted; prints a message asking for it not to be substituted.
{{can be substituted}} – For the doc of templates whose substitution is optional.
{{may be substituted}} – Same as the template above, but with the adverb may being used in the notice (instead of can).
{{substitution}} – Allows free-fill description of whether the template should be substituted and under what conditions.