A mechanism is available for identifying specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon. We feel that indiscriminate (and unfortunately wide-spread) use of such jargon is a greater barrier to understanding and using Web content than is implied by its relegation to level 3.
Should be a level 2 criteria
SC 3.1.3 (formerly 3.1.5) is a level AAA success criterion because it cannot be applied to all web pages. Content in some fields would become extremely difficult to read if *all* specialized vocabulary had to be defined either inline or via linking, even when the terms are well known in their respective fields. Jargon is typically a barrier for people who are not in the field where the jargon is used-- e.g., the jargon of literary history may be problematic for chemical engineers but not for literary historians. Practitioners in a field are likely to provide definitions when introducing new terms or re-defining existing ones-- even when they are writing for their professional peers.
We have added information to the Intent section, encouraging authors to satisfy this success criterion even for lower levels of conformance for specialized information intended for non-specialist readers.