VSE/POWER can be an application to the TCP/IP product distributed with z/VSE. When VSE/POWER has no data to send, the TCP/IP product itself decides to send some 'keep-alive' data now and then to avoid that the connection is dropped. Because other TCP/IP products or some network controller do not understand the meaning of 'keep-alive' data (although it is well defined according to the TCP/IP architecture), a connection may nevertheless be dropped in some network configuration. To avoid this dropping, VSE/POWER sends an 'empty' buffer every two minutes. An empty buffer consists of some control bytes indicating a length of zero userdata.