Opc.Ua.Server.CoreNodeManager.ValidateFilter C# (CSharp) Method

        private ServiceResult ValidateFilter(
            NodeMetadata    metadata, 
            uint            attributeId, 
            ExtensionObject filter, 
            out bool        rangeRequired)
        {
            rangeRequired = false;

            // check filter.
            DataChangeFilter datachangeFilter = null;

            if (filter != null)
            {
                datachangeFilter = filter.Body as DataChangeFilter;
            }
            
            if (datachangeFilter != null)
            {
                // get the datatype of the node.                
                NodeId datatypeId = metadata.DataType;
                
                // check that filter is valid.
                ServiceResult error = datachangeFilter.Validate();

                if (ServiceResult.IsBad(error))
                {
                    return error;
                }
                
                // check datatype of the variable.
                if (!m_server.TypeTree.IsTypeOf(datatypeId, DataTypes.Number))
                {
                    return StatusCodes.BadDeadbandFilterInvalid;
                }

                // percent deadbands only allowed for analog data items.
                if (datachangeFilter.DeadbandType == (uint)(int)DeadbandType.Percent)
                {
                    ExpandedNodeId typeDefinitionId = metadata.TypeDefinition;

                    if (typeDefinitionId == null)
                    {
                        return StatusCodes.BadDeadbandFilterInvalid;
                    }
                    
                    // percent deadbands only allowed for analog data items.
                    if (!m_server.TypeTree.IsTypeOf(typeDefinitionId, VariableTypes.AnalogItemType))
                    {
                        return StatusCodes.BadDeadbandFilterInvalid;
                    }

                    // the EURange property is required to use the filter.
                    rangeRequired = true;
                }
            }
        
            // filter is valid
            return ServiceResult.Good;
        }