The minimum size of content (in megabytes) that will cause a request for a wakeup. See Integrating with WakeUp for more details.
Registry valueDefault valueNotesInstaller property

Any content below this size is downloaded from the DP as downloads from the DP for files this size will likely complete before any wakeups will have had a chance to finish. The value can be 0, in which case wakeups will always be attempted.

For example, if it is set to 512 and size of the content downloaded is 500 MB, a wake-up request (to site or subnet) is not be sent. Similarly, if size of the content is 600 MB, then wake-up requests (to site and subnet, determined by WakeupEnabled) is be sent.

For standalone downloads (using SMSNomad.exe) and under WinPE, there has no effect as the size of the content cannot easily be determined. Wake-up requests are always sent in these instances.