(OSI-RM, OSI Reference Model, seven layer model) A model of network architecture and a suite of protocols (a protocol stack) to implement it, developed by ISO in 1978 as a framework for international standards in heterogeneous computer network architecture.
The OSI architecture is split between seven layers, from lowest to highest: 1 physical layer, 2 data link layer, 3 network layer, 4 transport layer, 5 session layer, 6 presentation layer, 7 application layer.
Each layer uses the layer immediately below it and provides a service to the layer above. In some implementations a layer may itself be composed of sub-layers.
OSI is the umbrella name for a series of non-proprietary protocols and specifications, comprising, among others, the OSI Reference Model, ASN.1 (Abstract Syntax Notation 1), BER (Basic Encoding Rules), CMIP and CMIS (Common Management Information Protocol and Services), X.400 (Message Handling System, or MHS), X.500 (Directory Service), Z39.50 (search and retrieval protocol used by WAIS), and many others. Apart from its actual application to real protocols, it also serves as a useful teaching model.
- Open telecom platform
communications, library, Erlang (OTP) A set of standard, open source libraries and tools for use with Erlang. (http://erlang.org/faq/t1.html#AEN17). (2001-08-28)
- Open texture
noun 1. (philosophy) the failure of natural languages to determine future usage, particularly the ability of predicates to permit the construction of borderline cases
- Open the door to
Also, open doors. Create an opportunity for, as in Legalizing marijuana may open the door to all kinds of abuse, or Her statement opened the door to further discussion, or Dad’s connections at the hospital have opened doors for Richard’s colleagues at medical school. [ Late 1600s ]
[oh-puh n-tim-berd] /ˈoʊ pənˈtɪm bərd/ adjective, (of a roof, ceiling, etc.) 1. constructed so that the timbers are exposed.