$id
$id : string
Everything the settings form needs to say about one codec.
Three things together, because an administrator deciding whether a compressor is worth installing needs all three at once and none of them is useful alone: what it costs in size and speed, whether this machine can run it, and if not, the exact command that fixes that.
The reference measurements are shipped figures from a fixed Drupal-shaped corpus, so two hosts can be compared. They are NOT a promise about a particular site: ratio depends heavily on what the content is, and a corpus with a lot of hashes or already-compressed media will do worse than one that is mostly prose and repeated field structure. Calibrator measures the real thing on site data and marks those figures as such, and the form shows both.