The DWG format is a special type of file that is designed to store two-dimensional and three-dimensional project data and metadata. This format was developed by Mike Riddle in the late 1970s for Interact CAD, and then Autodesk licensed it in 1982 and began to use it as the main format for storing its image files.
To date, the DWG format has two specifications. The first of them was developed by the non-profit consortium Open Design Alliance and can be found on the Internet. And the specification from Autodesk is available only to those developers who have been registered and approved by this company. It is known that with the advent of each subsequent version of AutoCAD, changes are made to the DWG file format. Before the 11th version of this program was released, the DWG format changed to a small extent. As a rule, the changes concerned only those moments that were associated with the new features of the new versions that appeared. In version 12 of AutoCAD, the DWG format almost remained unchanged, but this happened only because AutoCAD13 was created to work with a practically new DWG format.
In the future, with the advent of the 14th and later versions of AutoCAD, more and more new changes to this file type occurred.
Since the DWG format was never published, many developers of various software have attempted to decode it and use it in creating commercial programs. For example, various dDWG converters and applications for viewing files of this type were created.
As a result, despite the resistance of Autodesk, the OpenDWG Alliance was created - an open community with the goal of making this format accessible to all members of this alliance.
In order to be able to exchange drawings between AutoCAD and any other program, Autodesk proposed using the DXF format. It has open source code, and a specification for it is included in each set of documentation for AutoCAD.
Autodesk is not going to share its monopoly on this format with anyone. Evidence of this is TrustedDWG technology, which is built into the latest versions in AutoCAD. Its purpose is to check the type of file to open and notify the user if it turns out that the file is not saved in an application developed by Autodesk or a program developed under the RealDWG ™ license. This technology does not make it possible to correct possible errors in a file, and it is up to the user to decide whether to open such a file or not. However, this option can be disabled in the program.
Suppose you come across a file whose format is DWG. How to open it and view the information stored in it? If your profession is by no means connected with the design and creation of drawings, then it is not at all necessary to search on the Internet for paid and voluminous AutoCAD. You can use the free DWG TrueView ™ utility, which, in addition to viewing, can convert and convert drawings, as well as print them. Domestic developers suggest using the nanoCAD program to work with the DWG format. This application has two versions: free and paid, containing improved functionality, a PDF printer and a number of other useful additions.
It happens that when creating a complex drawing that took half a day (if not a whole day), the program generates an error and closes, the file gets corrupted and does not want to open later. This problem mainly affects older versions of AutoCAD. In this case, you do not need to tear your hair out, but you should try to restore the information as follows. First, you should search in the folder where your file was saved, a copy with the bak extension. If there are several, then you need to take the latest version. Then copy it to another location, change the extension to DWG and try to open it again. If this does not help, then you can try to fix the errors in the damaged file in a more recent version of AutoCAD, and then save the file in the correct version.