NOTE: Tags do not apply to Template expressions, instead you use Template Parameters.
To use an OPC historic tag in an expression, you can either type in the tag manually, or you can use the Select Historic Tag window. An OPC Historic tag calculates a value from a database item that has historic data.
To use the browse button to insert an OPC historic tag, see Selecting an OPC Historic Tag.
To enter an OPC historic tag manually, see Syntax of an OPC Historic Tag.
To reference an OPC historic tag using a search key, see Search Keys for OPC Historic Tags.
Further Information
Configuring Search Keys: see Extra Database Fields in the Geo SCADA Expert Guide to Server Administration.
Accessing Search Key Tags (OPC Historic Data): see Access Historic Search Key Tags in the Geo SCADA Expert Guide to Core Configuration.