Complex sentence: In a modified semi-block format letter, all text is left aligned (except the author's address, date, and closing), paragraphs are indented, and the author's address, date, and closing are usually indented in same position.
Split into simpler sentences: In a Modified Semi-Block format letter, (1) all text is aligned to the left margin, except for the author's address, date, and closing; and (2) paragraphs are indented. The author's address, date, and closing are usually indented in same position.