[[Documentation]] *Introduction LMNtal is a concurrent language based on hierarchical graph rewriting. It features: -rule-based multiset transformation of graph nodes, -symbolic names attached to nodes, -bidirectional 1-to-1 links connecting graph nodes together, -hierarchically nested membranes grouping multisets of nodes, -locality of rules, -dynamic process/rule migration, -inherent graphical view of programs, -uniform treatment of processes and data, -nd more.... Figures of hierarchical graphs are being prepared....