The term 'slot' is used in the context of the Eddystone beacon specification.
I cannot find a definition of that word.
For example, the sample app from Nordic says "The example provides five advertising slots" and despite working in Bluetooth for 17 years I am confused :-)
Does it mean that if you have 5 slots, then each advert will contain one frame and so 5 adverts are required to advertise all of them, OR Does it mean that you can fit 5 AD elements in a single advert ( which means it will not fit in pre v5 adverts)
I think in my case the confusion comes from a little bit too much knowledge to be able to perceive the ambiguity.
Look forward to hearing from someone.
Note to Nordic guys: it may be worth putting whatever feedback comes back as a response to this in the Nordic Inforcenter page related to "Eddystone Beacon Application"