The left-hand margin should be three-quarters of an inch, with paragraph Indention an inch more.
"The Etiquette of To-day"
Edith B. Ordway
Write verse as verse; do not give it equal Indention or length of line with prose.
"The Century Handbook of Writing"
Garland Greever Easley S. Jones
27 10. Indention of subclasses.
"The Classification of Patents"
United States Patent Office