...to make it more clear that those words have a strict definition behind them. (http://www.ietf.org/rfc/rfc2119.txt) W3C does it as well in their specs.
We already have this in 1.3 of the main spec:
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in IETF RFC 2119.
...to make it more clear that those words have a strict definition behind them. (http://www.ietf.org/rfc/rfc2119.txt) W3C does it as well in their specs.
We already have this in 1.3 of the main spec:
Should be put into the profiles spec as well.