Sentence:  Also it giueth a great grace to your writing, if the <WSD>whites</WSD> of certeine letters bee made of one equall bignesse with the o. supposing the same were all round, as the <WSD>white</WSD> of the b. of the a. p. y. v. w. x. q. d. g. and s. 
Meaning of the word marked with <WSD> tags:  The enclosed part of a letter of the alphabet, especially when handwritten.