Type O7. The vertical line of the right numeral box has a minute break about 0.4 mm from the top; the lower left frame junction line is unbroken.
“It is the very small break (or narrow spot) in the vertical line of the right numeral box that distinguishes this type from Type O6.”
Type O6. The vertical line of the right numeral box and the lower left frame junction line are unbroken.
“This type closely resembles Type O2 and has the same characteristics, but the vertical line in the left numeral box is narrower than in Type O2.”
Type O1. The vertical line of the right numeral box retouched.
Type O2. The vertical line of the right numeral box is unbroken and not retouched; the lower left frame junction line unbroken.
Type O3. The vertical line of the right numeral box is broken near the top and is weak at the middle; the lower left frame junction line is unbroken.
Type O4. The lower left frame junction line is weak or broken above the top of the spandrel.
Type O5. The lower left frame junction line is weak or broken both above and below the top of the spandrel.
Type ERO1. The lower left frame junction line and the vertical line of the left numeral box are unbroken.
