What is Bandwidth and Dsync in the P menu?

[Hellop 0]

Bandwidth and Desync don't seem to be defined anywhere.  I have seen forum posts that say that Bandwidth is in centi-bits.  That is, 100 in the bandwidth field = 10Kilobits.

People, regardless of ping seem to go through this pattern when connecting (on the one map I monitored): They start with about 50-100 "bandwidth" for a few seconds.  Then their Bandwidth jumps to around 3000.  Then over a period of 10-20 minutes it slowly drops down to 50-100, just like everyone else.

Desync has something to do with lag, but is it frames, time, bits or what?

So, can someone specify what the units of Bandwidth and Desync are?