The first line of the definition specifies the macro name and any parameters. Parameters are named and can optionally have default values that are used if the parameter isn't specified at the time of calling. The body of the macro definition follows, terminated with `\end`. The macro can include parameters using the `$name$` construction.
Macro definitions must be placed at the top of a tiddler. Macros are available to the tiddler that defines them, plus any tiddlers that it transcludes.
There are many different ways to invoke macro.A macro called `italicise` that takes a single parameter called `text` can be invoked in any of these ways:
```
<<italicise "Text to be made into italics">>
<<italicise text:"Text to be made into italics">>
<$macrocall $name="italicise" text="Text to be made into italics"/>
<$macrocall $name="italicise" text={{Title of tiddler containing text to be italicised}}/>
<$macrocall $name="italicise" text=<<textMaker "Another macro to generate the text to be italicised">>/>