I`ve come across references to suspension shimming, what is this, and how does it affect a forks small bump responses?

with reference to RS Revs i`ve also seen threads that refer to use of the floodgate to give a smoother more supple fork (open floodgate with mid point + closure on compression), is this an example of smimmimg and is it a good way to get a supple fork for small bumps whilst maintaining control over bigger hits?

Shims control the flow of oil in sophisticated forks – basically a pile of flexible metal discs that bend under pressure to allow oil thru ports.

Add more shims = less oil flow = more damping

Nothing to do with floodgates apart from some floodgates use a shim stack to provide a blow off point. I don’t think RS forks use a shims stack.

Using the lockout / floodgate to provide damping control is IMO a way of masking faults with set up in other areas.

Thanks for easy explanation; so basically youre saying that as long as I can get air pressure setup to give correct amount of sag for my riding style (say 20% on a 150mm fork) the floodgate should only be used to give me anemergency` blow off when I use teh fork lockout, and all other fine adjustmenst should be through compression and damping dials only?

That would be my point of view – others will disagree and there are different lockout models some of which are more sophisticated than others and some folk believe floodgate settings have an influence even when the lockout is off.

Myself I never use a lockout on any of my forks. I don’t find bob an issue and can get the fork set up to my liking without.