WXmodem, short for "Windowed Xmodem", is a variant of XMODEM developed by Peter Boswell in 1986 for use on high-latency lines, specifically public X.25 systems and PC Pursuit. These have latencies that are far higher than the plain-old telephone service, which leads to very poor efficiency in XMODEM. Additionally, these networks often use control characters for flow control and other tasks, notably XON/XOFF will stop the data flow. Finally, in the case of an error that required a resend, it was sometimes difficult to know whether a SOH was a packet indicator or more noise. WXmodem adapted XMODEM-CRC to address these problems.