For example, a format that says “%.6u” would generate six-digit numbers padded with zeros: 001234.
% indicates the start of the number definition.
.6 indicates that the numbers should have six digits. Numbers with less than six digits will be padded with zeros.
u indicates that the number is an unsigned integer (that is, it cannot be a negative number).

Checksheet settings are not defined at this site – Options are applied to this site from the first site above it in the hierarchy where checksheet export options have been selected
Checksheet settings are defined at this site – Checksheet export settings defined for this site also apply to all sites below it in the hierarchy