Early English clarification

The documentation for "early English" on the website states the following:

   And to put the endings into the English stemmer, the list

      ed   edly   ing   ingly

   of Step 1b should be extended to

      ed   edly   ing   ingly   est   eth

   As far as the Snowball scripts are concerned, the endings
   'est' 'eth'  must be added against ending  'ing'.


That last sentence is confusing. It appears to be describing an additional
step that needs to be taken. That is, after adding "est" and "eth" to the
list in Step 1b, the endings "est" and "eth" must be added against ending
"ing" in the Snowball scripts. But I assume the "Snowball scripts" are the
very thing we're modifying when we add "est" and "eth" to the list in Step
1b. So perhaps the last sentence is merely descriptive of what we've just
done. If we interpret the sentence that way, it could be written "In other
words, as far as the Snowball scripts are concerned...."

So am I correct in saying that an "early Modern English" stemmer can be
constructed from the existing English stemmer by simply adding "est" and
"eth" to Step 1b in the English stemmer, and that no additional changes
have to be made anywhere else?

Craig