It mean what you don't what does it mean.
It is misleading to use the mean as a descriptor of a data set when the median or mode would be more representative of the data set as a whole.
BDT means "Buffer Descriptor" in the USB jargon
after is a time descriptor
I believe the descriptor is: Evap Low Pressure (related to fuel tank)
In computer programming, a file descriptor (FD) is an abstract indicator for accessing a file. The term is generally used in POSIX operating systems.
it's a size descriptor