You can automatically update IDF files from older versions to a current version in EP-Launch's File menu or as a standalone program called IDFVersionUpdater, but there is nothing like this that will automatically convert IDF files "backward" to older versions. If you want to do this, you will need to follow this procedure:

1. Make a copy of your v9.2 IDF that you will then convert "backward" to a v8.4 IDF
2. Compare compare the Input Data Dictionary (IDD) file for each version to see what input field rules have changed between the versions, or if the object in the new version was even available in the older version.
3. Use the IDD file differences to edit the v8.4 IDF in a text editor since opening this IDF in IDF-Editor for v8.4 will likely not work because of these IDD file differences

version. For example, if your v9.2 IDF has a PerformancePrecisionTradeoffsFoundation:Kiva object, object for ground-contact surfaces, you couldn't use that in v8.4 because it was only added in v9.2. Another example v8.7. You would then have to make a copy of your v9.2 IDF and manually update it to v8.4 based on these IDD changes, which will be the RunPeriod object, which had various input field rules changes between v8.4 and v9.2 (Name input field is required and can't be left blank, new input fields added a very time-consuming process for Begin Year and End Year, etc.). Screenshots larger models.

See examples below illustrate how these examples are found while of comparing two IDD files using Beyond Compare (free diff tools like WinMerge would also work).

New object that didn't exist in older version

Object has rule changes to input fields from older version

You can automatically update IDF files from older versions to a current version in EP-Launch's File menu or as a standalone program called IDFVersionUpdater, but there is nothing like this that will automatically convert IDF files "backward" to older versions. If you want to do this, you will need to compare the Input Data Dictionary (IDD) file file for each version to see what input field rules have changed between the versions, or if the object in the new version was even available in the older version. For example, if your v9.2 IDF has a Foundation:Kiva object for ground-contact surfaces, you couldn't use that in v8.4 because it was only added in v8.7. You would then have to make a copy of your v9.2 IDF and manually update it to v8.4 based on these IDD changes, which will be a very time-consuming process for larger models.

See examples below of comparing two IDD files using Beyond Compare (free diff tools like WinMerge would also work).

New object that didn't exist in older version

Object has rule changes to input fields from older version