The "Limit of Course Structure" tells you something about to point until which the autopilot can coupled as far as I understood. Letter E for example represents roll out guidance.
@MoodyBlue: I am aware of the Quick References Pages of some of our local airlines but it is concerning me that a lot of operators are not aware of this ILS performance class. Until a few years ago ATC was only informing pilots of the supported category. And ATC determined (they are technical owner of system) which category was supported (based on the III/E/2 for e.g.). So what actually happened is that this check shifted (or is shifting) from ATC to the cockpit (sounds like a liability issue).
Reading the reactions on this topic I am still concerned that at the moment we stop with sending this supported category on ATIS we get discussions on the frequency.
Thx for your reactions till so far
