current: 

QUOTE cite="http://dev.w3.org/html5/spec/editing.html#the-accesskey-attribute"
    1. If the element has no accesskey attribute [1], then skip to the
       fallback step below.
[snip]
    4. Fallback: Optionally, the user agent may assign a key combination
       of its choosing as the element's assigned access key [2] and then
       abort these steps.
UNQUOTE

[1] http://dev.w3.org/html5/spec/editing.html#the-accesskey-attribute
[2] http://dev.w3.org/html5/spec/editing.html#assigned-access-key


PROBLEM: 

1. combining steps one and four results in the following ambiguous 
rule:

"If no accesskey has been defined for the element, the user agent may 
assign a key combination of its choosing as the element's assigned access 
key and then abort the steps"

this is insufficient for the following reasons:

1.1. if the user agent assigns a key combination of its own as an 
element's assigned access key, the user agent MUST notify the user 
what accesskeys have been assigned to which elements;

1.2. if the user agent assigns a key combination of its own, such an 
assignment MUST not conflict with author-defined accesskeys; this means
that the author-defined access keys MUST be omitted from the collection
of user-agent assigned keys


REPLACE WITH:

  4. Fallback:

     A. if the user agent assigns a key combination of its own as 
        an element's assigned access key, 

            1. the user agent MUST notify the user what accesskeys 
               have been assigned to which elements;

            2. such an assignment MUST not conflict with 
               author-defined accesskeys; this means that the 
               author-defined access keys MUST be omitted from the 
               collection of keys available for the user-agent to 
               assign;

     B. Abort these steps