Sentence:  [p 88] Because Elizabethan <WSD>spelling</WSD> was fluid, editors feel free to ‘modernize' (correct) the <WSD>spelling</WSD> in the quartos and the Folio. But how is one to spell Rosencratz or Guildenstern, where the <WSD>spelling</WSD> varies, not only from text to text, but even within texts? 
Meaning of the word marked with <WSD> tags:  The manner of spelling of words; correct spelling.