"The explanation of how to use printf formatting is in the help for sprintf. (the printf help really should point to this too)." [my emphasis]

The printf documentation does point to this. It starts with:

"Equivalent to print FILEHANDLEsprintf(FORMAT, LIST), ..."

[FWIW, madM has already been provided with that information (in Re: printf matrix) as well as example sprintf usage in a number of places.]