\begin{tabbing}
component{-}compatible\=\{i:l\}\+
\\[0ex](${\it ds}$; ${\it da}$; $T_{1}$; $T_{2}$; $C_{1}$; $C_{2}$)
\-\\[0ex]$\,\equiv$$_{\mbox{\scriptsize def}}$$\;\;$\=$\forall$$X_{1}$:Interface(${\it ds}$;${\it da}$;$T_{1}$), $X_{2}$:Interface(${\it ds}$;${\it da}$;$T_{2}$).\+
\\[0ex]scheme{-}compatible\=\{i:l\}\+
\\[0ex]((($C_{1}$($X_{1}$)).1); (($C_{2}$($X_{2}$)).1))
\-\-
\end{tabbing}