There are plenty of articles on the web detailing why you might not want to use Apache's default inode-mtime-size format for ETags (see e.g. here or here). All such articles recommend the same thing: remove inodes from your ETags.
But I have yet to read anything on what might have motivated the inclusion of inode for Apache in the first place. On the face of it, it only seems useful if one needs to be able to differentiate between octet-for-octet facsimiles of the same resource, but this is surely counter to the very purpose of ETags.
Apache's authors are not known for their sloppy handing of internet standards, so I feel I must be missing something. Can anyone elaborate?