When using HAMMER CONNECT in the AutoCAD environment, there are three files that fundamentally define a HAMMER CONNECT model hydraulic model:

• Drawing File (.dwg)—The AutoCAD drawing file contains the custom entities that define the model, in addition to the planimetric base drawing information that serves as the model background.
• Model File—The native HAMMER CONNECT model database file that contains all the element properties, along with other important model data. HAMMER CONNECT .etc files can be loaded and run using the Stand-Alone Editor. These files may be copied and sent to other HAMMER CONNECT users who are interested in running your hydraulic model. This is the most important file for the HAMMER CONNECT model.
• wtg Exchange Database (.wtg.sqlite)—The intermediate format for wtg hydraulic model files. When you import a wtg file into HAMMER CONNECT, you first export it from wtg into this format, then import the .wtg.sqlite file into HAMMER CONNECT. Note that this works the same in the Stand-Alone Editor and in AutoCAD.

The three files have the same base name. It is important to understand that archiving the drawing file is not sufficient to reproduce the model. You must also preserve the associated .etc and wtg.sqlite file.

Since the .etc file can be run and modified separately from the .dwg file using the Stand-Alone Editor, it is quite possible for the two files to get out of sync. Should you ever modify the model in the Stand-Alone Editor and then later load the AutoCAD .dwg file, the HAMMER CONNECT program compares file dates, and automatically use the built-in AutoCAD synchronization routine.