\newcommand{\const}[1]{%
\index{#1@{{\tt {#1}} (costante)}}\texttt{#1}%
} % constant name
+\newcommand{\direct}[1]{%
+\index{#1@{{\tt {#1}} (direttiva)}}\texttt{#1}%
+} % constant name
\newcommand{\file}[1]{\texttt{#1}} % file name
\newcommand{\link}[1]{\texttt{#1}} % html link
\newcommand{\ctyp}[1]{\texttt{#1}} % C standard type