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.
This attribute shows the bottom level of a single part, cast unit, assembly, part of a connection, or a pour object by the global axis. BOTTOM_LEVEL_GLOBAL takes the unit and accuracy from the MarkDimensionFormat.dim dimension property file. You can modify the settings saved in MarkDimensionFormat.dim in the dimension property pane in an open drawing.
You can use this attribute as a user-defined attribute in part marks and associative notes, and also in reports and templates.
With content types REBAR and SINGLE_REBAR, and in rebar marks, this attribute shows the bottom level of a single reinforcing bar, bar group, or rebar set bar group by the global axis. For bar groups, the SINGLE_REBAR row shows the value of the whole group, not the values of individual bars.