Surface Modeling (Editing and Adding Boundaries or Edge Breaklines or manipulating Properties etc.) is in the Surface Modeling Edition of TBC. That also includes CAD Editing and Exports to a variety of Formats. including DXF, DWG, LandXML, and a host of others as well. I would recommend that for anyone wanting to manipulate imported surface data.
Tim was correct in saying the Free Version allows you to import a LandXML file and if it contains a Surface as a TIN Model or as Points, Breaklines and Boundaries, TBC will bring in the data, create the Points, Lines and Surfaces and allow you to query them and View them in Plan, Slicer or 3D Views. The free version will also allow you to then use the Field Data commands to export those files as Surfaces, Linework or Stakeout Points to the SCS900 / Siteworks or GCS900 / Earthworks or PCS900 systems. However if the imported data has any problems at all reqyuiring edits, you will either have to go back to the source software and fix them there and then re export / re import to TBC or purchase a license of TBC.
TBC is licensed primarily as Editions of the software. The Surface Modeling Edition would be required to edit the models and finish them up ready for machine control or survey / site positioning purposes. That will also compute volumes etc. as well.
Your local SITECH will be able to provide you with a quote for the software and any training that you may require.
Alan