On the number of L-shapes in embedding dimension four

\textit{Minimum distance diagrams}, also known as \textit{\textsf{L}--shapes}, have been used to study some properties related to \textit{weighted Cayley digraphs} of \textit{degree} two and \textit{embedding dimension three numerical semigroups}. In this particular case, it has been shown that these discrete structures have at most two related \textsf{L}--shapes. These diagrams are proved to be a good tool for studing \textit{factorizations} and the \textit{catenary degree} for semigroups and \textit{diameter} and \textit{distance} between vertices for digraphs.