Sentence:  The words "jot" and "<WSD>tittle</WSD>" in this passage refer to diacritic marks, that is, dashes, dots, or commas added to a letter to accentuate the pronunciation. 
Meaning of the word marked with <WSD> tags:  Any small dot, stroke, or diacritical mark, especially if part of a letter, or if a letter-like abbreviation; in particular, the dots over the Latin letters (i) and (j).