Whilst we aim to minimise the need for changes to existing configurations, occasionally a change to the object model will need to be made (usually in the interests of flexibility and clarity) that results in changes to the way options are expressed.

During a software upgrade that requires changes to be made the current config will be automatically transformed so that things keep working as they were before wherever possible.

We need to keep track of transformations that are not idempotent (that is applicable repeatedly without side effects). The patch attribute notes the config version to avoid those transformations being applied repeatedly.

Configs downloaded from the FireBrick will have the patch attribute, so that if they are stored and uploaded to a later version they will be correctly transformed. However the transformations aren't kept around forever, and are periodically cleared out in breakpoint releases (see Section 4.3.1.1 for more info).

If you wish to upload a config targetted for the current version without transformation simply omit the patch attribute.

The FB2900 will warn during the upload of configurations with a patch version higher than that supported bv the software.