Begins a list of attributes and arguments for a <tag>, <data-tag>, <macro> or <command>.
In the case of tags, the signature should contain <attribute> tags. Macros expect <argument> tags. For a command, the signature should contain <arg> and <option> tags.
<tag name="fib"><doc>Calculate the fibonacci sequence</doc><signature><attribute name="count" type="integer" /></signature><let fib="[0, 1]"/><repeat times="count - 2"><append value="fib[-1] + fib[-2]" dst="fib" /></repeat><return value="fib" /></tag>