\begin{definition}[Definition:Rule of Formation]
Let $\FF$ be a formal language whose alphabet is $\AA$.
The '''rules of formation''' of $\FF$ are the rules which define how to construct collations in $\AA$ which are well-formed.
That is, the '''rules of formation''' tell you how to build collations featuring symbols from the alphabet $\AA$ which are part of the formal language $\FF$.
The '''rules of formation''' of a formal language together constitute its formal grammar.
There are no strict guidelines on how a '''rule of formation''' should look like, since they are employed to ''produce'' such strict guidelines.
Thus, these '''rules of formation''' are often phrased in natural language, but their exact form is to some extent arbitrary.
\end{definition}