These extensions include, among others, ODBC (called the "crowning jewel of WOSA"), TAPI, WOSA/XFS, SAPI and MAPI, and their supporting services, as well as the abstraction of access to printers, modems, and networking services, which run identically over TCP/IP, IPX/SPX, and NetBEUI.
Included in the Windows Sockets API version 2.0 are functions to use IPX/SPX, although the protocol was all but obsolete already at the time WSA 2.0 shipped.
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It also formalized support for multiple protocols, including IPX/SPX and DECnet.
Sequenced Packet Protocol (SPP) was an acknowledged transport protocol, analogous to TCP; one chief technical difference is that the sequence numbers count the packets, and not the bytes as in TCP and PUP's BSP; it was the direct antecedent to Novell's IPX/SPX.
The novel details how Anna became involved with the IPX expedition to Z'ha'dum, how she met Morden and how she became the Shadow-infested shell of who she had once been who returned to the station in the final episode of season three of Babylon 5.
Although this market segment is now much reduced, the technologies developed in this area continue to be influential on the Internet and in both Linux and Apple Mac OS X networking—and the TCP/IP protocol has now almost completely replaced IPX, AppleTalk, NBF, and other protocols used by the early PC LANs.
Roughly speaking, tunneling protocols operate at the transport layer, such as carrying non-IP protocols such as IBM's SNA or Novell's IPX over an IP network, or end-to-end encryption with IPsec.