In plain language
Devices that manage EDID store a library of tables. Some are read-only presets covering common formats; some are writable slots you fill yourself, either by uploading a file or by capturing the EDID currently in use.
Why it matters in your setup
Slots turn a working configuration into something repeatable. Get a chain running correctly, save the EDID that made it work, and you can return to it after any change — or reproduce it on a second system.
They also make comparison quick. Two candidate EDIDs in two slots means switching between them takes a click instead of a rebuild, which is how you find out which one your source actually prefers.
What the DR HDMI 8K does with it
The DR HDMI 8K has 100 tables: ninety presets plus ten custom slots. Slots 1 to 10 come pre-filled with real display profiles, you can upload your own EDID binary into any of them, and SAVE ACTIVE EDID TO CUSTOM EDID # captures whatever is currently running into slot 8, 9 or 10. Selecting a slot loads it and fires a hot plug so the source re-reads it.
Need the hardware?
Open the DR HDMI 8K product page on HDfury.uk.