A preamble is a signal used in network communications to synchronize the transmission timing between two or more systems. Proper timing ensures that all systems are interpreting the start of the information transfer correctly. A preamble defines a specific series of transmission pulses that is understood by communicating systems to mean “someone is about to transmit data”. This ensures that systems receiving the information correctly interpret when the data transmission starts. The actual pulses used as a preamble vary depending on the network communication technology in use.
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A preamble is an introductory and expressionary statement in a document that explains the document's purpose and underlying philosophy. When applied to the opening paragraphs of a statute, it may recite historical facts pertinent to the subject of the statute. It is distinct from the long title or enacting formula of a law.
In parliamentary procedure using Robert's Rules of Order, a preamble consists of "Whereas" clauses that are placed before the resolving clauses in a resolution (formal written motion). However, preambles are not required to be placed in resolutions. According to Robert's Rules of Order, including such background information may not be helpful in passing the resolution.
