Preceding action

[Péter]

Hi!

Can one assume anything about the order of grammar actions?
At a given action, can one be sure which action was the previous (just 
finished) action?

For example, in case of a list:

 list: element {/*action xx*/} | list ',' element {/*action yy*/};
 element: A | B | C | D ;

At action yy, is it true (always) that the (immediately) preceding action must 
be an action xx or action yy?

In other words: can one action start something and subsequent actions continue and finish it? For example, taking the 
list elements one by one, left to right, and appending them to a list (or concatenating to a buffer).


(I am not a list member yet, so please address or Cc to me.)
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