In Australia to comply with the ASX regulations, companies must continuously disclose all pertinent information. With a quick google search of; "ASX continuous disclosure requirements" you can find all of the specifics for what needs to be disclosed. However, I believe it is rather well summed up in this sentence.
"Once an entity is or becomes aware of any information concerning it that a reasonable person would expect to have a material effect on the price or value of the entity’s securities, the entity must immediately tell ASX that information."
If you have read the post before this on market efficiency, it should be pretty obvious that if complied with, this should dramatically increase market efficiency. There are many specifics in what a reasonable person would and wouldn't expect to effect the share price, but also where a trading holts and other situations can occur. I found this abridged version particularly useful for summing up the key points concisely.
http://www.asx.com.au/documents/about/abridged-continuous-disclosure-guide-clean-copy.pdf
As always, if you are interested in additional information either follow the link I provided or feel free to shoot me an email.