Template:1x/doc

As a meta-metatemplate
This template is particularly useful as a meta-metatemplate. A metatemplate can use, for example,  to generate an   tag. Unlike such a tag made with XML/HTML entities ( and  ), this tag will be evaluated when the resulting template is substituted.

To have an option that uses the return value of the template as an input
This template can be very useful if you want to have an option that uses the return value of the template as an input. For example, consider the following template: If the parameter sbc is defined, the result will be in small capitals using sbc. To test this sample, suppose the parameter is yes: The result will be:

Then suppose it is a null: The result will be: