With some commands, BricsCAD® will use different option names to AutoCAD®. With ROTATE, Base angle is the same as the AutoCAD® Relative option.
The official shortcut key in BricsCAD® is “B”, but guess what? The AutoCAD® shortcut of “R” still works
There are a few commands like this in BricsCAD®, but you often don’t notice because the AutoCAD® shortcuts simply work with no complaint.
With ROTATE you may like to try using “@” when ROTATE asks for a Base angle, BricsCAD® will use the initially picked Rotation point. “@” is shorthand for the Last Point entered.