Holds total numbers of bytes waiting to be received by your application.

A Long value.  

object.DataReady [= value]

The DataReady Property syntax has these parts:

DataReady property will return total number of bytes waiting to be received by your application using Receive method. This property can come handy when you need to make a decision if you will receive data or not - preventing Receive method to block if there's nothing already received.

You can set DataReady thus decreasing (or clearing) amount of data already in incoming buffer.