Last Post: May 20, 2010:
Regarding IEEE standards and free copies:
Once a new element of the standard (for example 802.11n) is rolled-up into the full standard, two things happen.
First, the new element (eg 802.11n) is removed from the free webpage. Second, the new full standard IEEE 802.11 (2009) is not there. It is only available for sale.
For another year, only the older full standard is available - e.g. 802.11 (2007). Afterward, the new standard (2009) will be available for free, and the older one (2007) will disappear.
So a rule of thumb is - that if you want a (free) copy of the smaller addendum, or the older full standard, before that year is up, get it while it is still listed.
PS - The interpretations that are sometimes available, can also be enlightening.