Syntactical structure (4)
FLAT vs DEEP structure: a flat CL has lots of commands at every level whereas a deep CL has a few basic commands which put the system into a level of input mode at which it will recognize certain commands. Advantage of a flat CLs is that they are very powerful (very complex command sequences can be expressed by stringing the right commands together, but require users to remember lots of command words (e.g. UNIX).
POSITIONAL vs KEYWORD: positional CLs have a strict syntax: the order in which command words are issued contains information (e.g. UNIX command: mv filename directoryname). For CLs which recognize keywords, the user can string commands together in any order - if there is potential ambiguity, the system will query/ask for confirmation before executing a command.
MNEMONICS: most CLs use abbreviated natural language words as commands to facilitate recall (e.g. mkdir for “make directory”).