If you are writing a lisp routine and you are trying to figure out if a command can be used in a lisp routine; try this...in the command line start by typing in a dash and then the command. For example...if you are wanting to create a new layer. In the command line type "-layer", then all the options show in the command line; Then just follow the prompts.
And at the end of it; if you are setting linetype, lineweight, color and the such...this is an example of what you will see...
If you have "Dynamic Input" turned on then it is easy to see what commands you can use the "-" in front of.