Time for action – marking keywords with optional formatting

We will use \newcommand another time, this time with an optional parameter concerning the formatting and a mandatory argument for the keyword:

1. Modify the previous example to get this code:

   \documentclass{article}
   \newcommand{\keyword}[2][\bfseries]{{#1#2}}
   \begin{document}
   \keyword{Grouping} by curly braces limits the
   \keyword{scope} of \keyword[\itshape]{declarations}.
   \end{document}

2. Typeset and check out the result:

   

What just happened?

Let's look again at the bold marked line in the code. By using [\bfseries], we introduced an optional parameter. We refer to it with #1. Its default value is \bfseries. Since we used a declaration this time, we added a pair of braces to ensure that only the keyword is affected by the declaration.

Later in the document, we gave [\itshape] to \keyword, changing the default formatting to italics.

Here's the definition of the \newcommand:

\newcommand{command}[arguments][optional]{definition}

command

The name...