part.autolabel — Specifies the labeling format for Part titles
If zero, then parts will not be numbered. Otherwise parts will be numbered, using the parameter value as the number format if the value matches one of the following:
Arabic numeration (1, 2, 3 ...).
Uppercase letter numeration (A, B, C ...).
Lowercase letter numeration (a, b, c ...).
Uppercase roman numeration (I, II, III ...).
Lowercase roman letter numeration (i, ii, iii ...).
Any nonzero value other than the above will generate the default number format (upperroman).