Creating Undo/Redo Files

Undo/Redo files can be created only after comparing two registry copies, i.e. these files can be created only from Compare window by clicking Save to Undo files or Save to Redo files button. Undo files consist of two file types: *.reg and *.inf (optional). They are in text format required by your system. To generate Undo, Redo for chosen nodes use the function of comparing within certain node and possibility to exclude some subnodes from comparing.

REG file begins with Delete section "DELETE section". It is followed by Add section "; ADD section"
To generate Undo, Redo for chosen nodes use the function of comparing within certain node and possibility to exclude some subnodes from comparing.

Add section of Undo.reg file contains Keys and Values Name found in the Old copy and not found in the New one, as well as Value Data from the Old copy modified in the New one.
Delete section contains Keys and Values found in the New copy and not found in the Old one.
INF file (optional) contains Values found in the New copy and not found in the Old one.

When Undo.reg and Undo.inf(optional) are executed, e.g. from Windows Explorer, the Registry is changed from New version to the Old one, and if the current version was New, the Old version is restored by executing these 1 or 2 files.

Redo files are created in the same way, but their function is reverse.

These files can be used, for example, to view changes in text format.

Caution! Use Undo/Redo files to modify the Registry only when this is absolutely necessary, having checked them before, if possible. Make sure you’ve backed up the Registry files (system.dat, user.dat, system.da0, user.da0) before using Undo/Redo files.

Why does one sometimes have to use *.inf files?

To our regret, it was impossible always to make a single file *.reg, as *.reg file is unable to remove some Values from the Registry.

To remove keys and key elements, an undocumented feature of REG files is used. If the line [-KeyPath] is introduced into REG file, the respective key will be removed.

For example, if you want to remove the elements Test2 Test4 in the key

KEY_LOCAL_MACHINE\SOFTWARE\Test
test1=val1
test2=val2
test3=val3
test4=val4

you have to create the following lines in REG file:

[-KEY_LOCAL_MACHINE\SOFTWARE\Test]
; Values to be deleted: "Test2" "Test4"
[KEY_LOCAL_MACHINE\SOFTWARE\Test]
test1=val1
test3=val3

where "; Values to be deleted: "Test2" "Test4"" - remark line, generated by ART.
If the key contains subkeys, for example: [HKEY_LOCAL_MACHINE\SOFTWARE\Test\Subkey1], removing elements in such keys using this method makes REG file very big and hard to read, as all the subkeys are to be restored, too. Therefore, in these instances the following lines are introduced into REG file, for example:

[KEY_LOCAL_MACHINE\SOFTWARE\Test]
; Value should be deleted: "Test2"
; Value should be deleted: "Test4"

These elements are removed either manually or using INF file, which will be created with the same name as REG, if you give positive reply on the message:

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