Context replication increases header compression gains by reducing the redundancy between flows via efficient replicate (IR-CR) packets. The optimum design of IR-CR packet formats requires elaborate understanding of the inter-flow redundancy. As context replication is most well-suited for TCP, this document presents a statistical analysis of TCP/IP inter-flow field behaviour. Based on the analysis, recommendations on ROHC-TCP packet format specifications for context replication are made. It is also shown that inter-flow field behaviour is inherently and significantly asymmetrical, and various ways of handling it are considered. Finally, based on the inter-flow behaviour of TCP Window field, it is noted that current encoding methods do not compress it efficiently.