For all Variablesspecified in this specification, the Attributesnamed in Table 6shall be set as specified in the table. The definitions for the Attributescan be found in OPC 10000-3.

Table 6– Common Variable Attributes




Optionally, a server-specific minimum sampling interval is provided.


The access level for Variablesused for type definitions is server-specific, for all other Variablesdefined in this specification, the access level shall allow reading; other settings are server-specific.


The value for the UserAccessLevel Attributeis server-specific. It is assumed that all Variablescan be accessed by at least one user.


For Variablesused as InstanceDeclarations,the value is server-specific; otherwise it shall represent the value described in the text.


If the ValueRankdoes not identify an array of a specific dimension (i.e. ValueRank<= 0) the ArrayDimensionscan either be set to null or the Attributeis missing. This behavior is server-specific.

If the ValueRankspecifies an array of a specific dimension (i.e. ValueRank> 0) then the ArrayDimensions Attributeshall be specified in the table defining the Variable.


The value for the Historizing Attributeis server-specific.


If the AccessLevelEx Attributeis provided, it shall have the bits 8, 9, and 10 set to 0, meaning that read and write operations on an individual Variableare atomic, and arrays can be partly written.