command by indirection

We know that the command to have children was laid on men, not on women, because G-d told Abraham that his seed would be as the stars in the sky.  G-d did not tell Sarah that she would be obligated to produce all those offspring. 

That is a direct command, even if the command itself is not presented as "you will do" this.  The command a direct command because it is understood from G-d's direct statement to the intended recipient.

A command by indirection would be that of covering one's head.

A rabbi friend of mine, for whom I have a great deal of respect, told his community that there is no command to cover the head.  Unfortunately, he is wrong, but that is only because when we think of commands, we think of them in "you will do" terms.

The command to cover the head is one we understand by indirection:  G-d tells Aaron to let his hair be wild.  Because we are not Aaron, we are NOT commanded to do as he did, therefore we cover the head.  That is a command of indirection (and thanks to haRav Dr Burton Visotzky for explaining this to my Midrash class.)