Select a relational domain ''X''<sub>''j''</sub> and one of its elements ''x''. Then ''L''<sub>''x''.''j''</sub> is a subset of ''L'' that is referred to as the ''flag'' of ''L'' with ''x'' at ''j'', or the ''x''.''j''-flag of ''L'', an object which has the following definition: | Select a relational domain ''X''<sub>''j''</sub> and one of its elements ''x''. Then ''L''<sub>''x''.''j''</sub> is a subset of ''L'' that is referred to as the ''flag'' of ''L'' with ''x'' at ''j'', or the ''x''.''j''-flag of ''L'', an object which has the following definition: |