The WHMCS documentation has a section on Option Flags:http://docs.whmcs.com/Crons#Option_Flags
At time of writing there are 20 options flags. None of the option flags have more detailed documentation. So while all the option flag are undoubtedly sensibly named, it's not certain what each one of them do. The WHMCS people have advised me that they're all "self explanatory", i.e. implying that no further documentation is required, but we're not so sure.
Therefore the "feature" I'm requesting is for more detailed documentation for each option flag to be written so that we can be a bit smarter about which ones we want to run - or not.