diff --git a/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/c_ConstraintDirichletBoundaryCondition.md b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/c_ConstraintDirichletBoundaryCondition.md
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index 0000000000000000000000000000000000000000..02834b84b65e939b0cc6ef27e2e8fdf2174e9f80
--- /dev/null
+++ b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/c_ConstraintDirichletBoundaryCondition.md
@@ -0,0 +1,2 @@
+For the constraint Dirichlet-type boundary condition the type has to be
+ConstraintDirichlet.
diff --git a/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraining_process_variable.md b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraining_process_variable.md
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index 0000000000000000000000000000000000000000..e333bfb00a055bae38529eaa85f8f2f33d62e903
--- /dev/null
+++ b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraining_process_variable.md
@@ -0,0 +1,2 @@
+This tag specifies the process variable whose flux values constrain the current
+process variable.
diff --git a/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraint_direction.md b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraint_direction.md
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index 0000000000000000000000000000000000000000..f1b350eb2b77253eed7e129d131281e75faba924
--- /dev/null
+++ b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraint_direction.md
@@ -0,0 +1,6 @@
+The value of the tag determines the evaluation of the constraint condition.
+Possible values for the tag 'constraint_directions' are 'greater' or 'lower'.
+
+If the value 'greater' is given the condition 'calculated_flux_value >
+constraint_threshold' is evaluated. If the value 'less' is given the condition
+'calculated_flux_value < constraint_threshold' is evaluated.
diff --git a/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraint_threshold.md b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraint_threshold.md
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index 0000000000000000000000000000000000000000..3f6784b236bd9a2be11be553ad51e2d1353e539c
--- /dev/null
+++ b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraint_threshold.md
@@ -0,0 +1 @@
+Threshold value used in the constraint condition.
diff --git a/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraint_type.md b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraint_type.md
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index 0000000000000000000000000000000000000000..11c0e76288a4a1eca33a93c2c070b5a704b6f2b8
--- /dev/null
+++ b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_constraint_type.md
@@ -0,0 +1,3 @@
+The constraint type has to be 'Flux', i.e., the constraint is based on the
+secondary variable. It is planned to add constraints based on the value of the
+primary variables.
diff --git a/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_parameter.md b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_parameter.md
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index 0000000000000000000000000000000000000000..f36803a9dcae4c1602b4fac0fb36f961aaf361c6
--- /dev/null
+++ b/Documentation/ProjectFile/prj/process_variables/process_variable/boundary_conditions/boundary_condition/ConstraintDirichletBoundaryCondition/t_parameter.md
@@ -0,0 +1 @@
+The name of the parameter that defines the Dirichlet-type condition values.