This is a template attribute. Template attributes can be used in filtering, or to retrieve data from the model to use in drawings and reports. For example, when you create a report, Tekla Structures replaces the attributes added in the report template with the corresponding object property values.

Use these attributes to show the weld effective throat. WELD_EFFECTIVE_THROAT shows the value for the welds above line, and WELD_EFFECTIVE_THROAT2 for the welds below line.