A mode may be a flag (e.g. +t), a string (e.g. +k), a number (e.g. +l), or a list of strings (generally masks, e.g. +b).
See Implementation
A mode may be a flag (e.g. +t), a string (e.g. +k), a number (e.g. +l), or a list of strings (generally masks, e.g. +b).