If this change is accepted, then also Part 5 should change: In ModelChangeStructureDataType Structure, field 'verb' (Table 156 in 1.04), there is currently Bit 4 for DataTypeChanged: "This verb may be used only for affected Nodes that
are Variables or VariableTypes. It indicates that the DataType Attribute has changed.". We should add bit 5 for ValueRankChanged.

I agree with the logic that ValueRank should be considered in the same way DataType is.

I agree - clients should be notified when any aspect of a Value changes - these can (and do) impact client behavior.

A change in any attribute that changes the "shape" of the data should trigger this event. This includes ValueRank, ArrayDimensions, and DataType; perhaps others, such as access rights, whether or not writes w/timestamps are supported, etc. Further, when any of these attributes change, all related attributes should be updated to the extent their new value can be ascertained.

For example,

• if the ValueRank changes to indicate the value is an array, the ArrayDimensions attribute should be updated to reflect the maximum length for all dimensions which are known.
• if the UA server "knows" that the max array length has changed, it should update the value in the ArrayDimensions and trigger this event.

This feature should be supported by a CU or facet that verifies this,

We agreed in the June 15 2021 weekly call that a change to ValueRank and ArrayDimensions should also be considered in the same way as a DataType change.

Need an errata for 1.04.

We agreed in the June 15 2021 weekly call that the description of Bit 4 "DataTypeChanged" will be modified to include ValueRank and ArrayDimensions along with the DataType.
We agreed not to add additional bits.

Need an errata for 1.04

Added ValueRank and ArrayDimensions in addition to DataType for the definition of DataTypeChange in Table 232 'ModelChangeStructureDataType'

Added Errata 1.04.11

Need to look at the bigger picture before committing to this solution.