The He Yi
Links: https://www.zhihu.com/question/20679872/answer/65565699
Source: Know
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To understand this problem, you first need to know
"Yuan"What is it.
Yuan (meta), which is generally translated into "about ... ... ".
In fact, the prefix is derived from the Greek, saying "in ... After the end of something, it contains the meaning of "inductive" and "summary". Therefore, the yuan, represents the "primitive", "system" meaning.
For example, in the literature field, there is a novel in postmodernism literature called "meta-fiction", which is "novel about fiction". "Traditional fiction is often concerned about the characters, events, is the content of the works, while the yuan novel is more concerned about how the author wrote the novel, often like to declare the author is in the fictional works, like to tell the reader the author is in what way to make a fictional work, more like to explain the author of the novel's All related processes." (Excerpt from Baidu Encyclopedia) ".
For example, British writer Ian McEwan's Work "Atonement". This book is about the younger sister Brioni because she fell in love with her sister Cecilia's boyfriend Robbie was he refused, because of revenge psychological mischief and framed him in prison, grown up in order to make up for the heart of guilt and enlisted to redeem the story. In this book, the protagonist Brioni is the "protagonist", is also the "author" of the book. It focuses on describing how Brioni wrote the book. This is the novel that concerns how the author writes the novel.
After understanding the meaning of meta, let's look at
meta Data .
Metadata (meta data)-data about data-is typically structured data (such as data stored in a database that specifies the length, type, etc.) of a field.
Metadata refers to the structured data (such as title, version, publication data, relevant description, including search points) extracted from the information resource to describe its characteristics and content, and to organize, describe, retrieve, save, manage information and knowledge resources.
For example, for a book (information Resource), we can retrieve the following information in the library system
A basic meta-data consists of metadata items and metadata content. Here, "title" is its metadata project, "Steve Jobs biography (United States) Walter Isaacson = Steve Jobs Walter Isaacson Eng" is the metadata content. For example, "author" and "publisher" are metadata items, while "Isaacson (Isaacson, Walter)" and "Citic Press" are metadata content. Learning a database should not be difficult to understand ~
By using metadata to describe resources, we can use it to do a lot of things. For example, identify resources, provide retrieval points for resources, and exchange data between different systems.
However, each of us can describe the resource, the name (metadata item) and the appearance of the value (metadata content) will be strange how to do?
As a result, there is a metadata standard.
Metadata standards include meta-data structure standards (i.e., metadata containing those items, Dublin Core set, Marc element set), metadata content standards, metadata criteria, metadata encoding standards (for storage and exchange of machine-readable records, such as Marc readable cataloging), XML)
Here we look at the details
Marc Format(a meta-data standard).
In the traditional library, we buy a lot of books. How can librarians know what books they have? We need to write the information for each book on a small card (some old library) and store it in your own library.
But with the development of computers, we think it is better to store the information of the bibliography in the computer. And with the development of the network, we feel that a library should be a grand coalition, all the book information are stored together. But each library has its own set of recording methods. As a result, the Marc format was born. Marc is designed to exchange bibliographic data and related information between systems after the advent of computers.
Of course, in the traditional library of the manual cataloging period, the use of terminology and the current computer catalog is different. For example, when we wrote the "meta-data" of a book on a card called "entry", and in a computer, the record of a book was called "Record". In a machine-readable catalogue, we called the item to be catalogued (the area of the item in the description) as the "field," and so on.
Having said so much, what is the MARC format like?
You can look at the CN-MARC format used in China. (Cnmarc is China's Marc format, which is written in the MARC format of the National Unimarc (UNIMARC specification). ）
It provides information on how the documentation resources should be recorded. For example, in the data field, it is defined for the 101 field:
101 0 $a text language $b intermediate Language $c original language
Then we'll catalog it into:
101 1 $achi $ceng (CHI is Chinese, Eng is English)
For example, it specifies that the 210 fields are catalogued as follows:
$c publication, issuer's name $d publication and issue date of $a publishing and issuing place
According to this request, we will write
$a Beijing $c Machinery Industry Press $d 2003
Next, the Internet is growing faster, the format of metadata more and more, people to its interoperability requirements are more and more high, there has been
XML！
When we use XML to describe a document, we can define our own tags, such as "<title>". These small tags are meta data.
In the network age, XML as a manifestation of metadata is very potential.
Finally, let's look at XML's good friend HTML.
HTMLIn the head there is a
Meta Tags。 So what is it?
According to the above explanation, we should know that it is "information about the document"
There are two types of meta attributes, name and HTTP-EQUIV.
The name attribute is used to describe the contents of a Web page so that search engines find it. Like the keywords of this webpage.
The Http-equiv property instructs the server to include a name/value pair in the header of the MIME document to be routed to the browser before sending the actual document.
Like what
<meta http-equiv= "Content-language" contect= "ZH-CN" > to illustrate the text and language used in home page authoring
What is metadata
