How are median dwell times calculated in Advan Neighborhood Patterns data?

I am wondering how the "MEDIAN_DWELL" variable is calculated in the Advan Neighborhood Patterns dataset. The variable description is somewhat vague:

"Median dwell time in minutes. Note that we are only including stops that have a dwell of at least 1 minute."

Does the median dwell time variable represent the median time a device spends in the CBG or the median dwell time for all the stops that occur inside the CBG?

For example, suppose a device enters a CBG at 3:00pm, makes a stop from 3:00-3:15pm, makes a second stop from 3:15-3:30pm, and then leaves the CBG at 3:30pm. If this were the only visit to the CBG, would the median dwell time be 30 minutes (the time the device spent in the CBG) or 15 minutes because there were two stops of 15 minutes each?