From OpenSCADAWiki
Generally, it is advisable to create such template (a layer above the physical data source object) above a raw data source that provides this data in attributes and without processing, and this template therefore performs:
- collection of these attributes of the raw source into items;
- processing of properties of the attributes;
- control and transmitting of commands of the values setting;
- processing of the violation conditions at single attributes and at the object in whole, together with which these violations can be fixed in the table of actual violations, typically by the alarmSet() function.