# Reference card

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> Markdown URL: https://mediated.wiki/source/Reference_card.md
> Source: https://en.wikipedia.org/wiki/Reference_card
> Source revision: 1287159472
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{Short description|Concise notes about a specific topic}}
{{for|the grid reference tool|Reference card (cartography)}}
thumb|Reference notes.
A '''reference card''', also known as a '''reference sheet''', '''quick reference card''', '''crib sheet''' or '''job aid''', is a concise bundling of condensed notes about a specific topic, such as mathematical formulas<ref name=DC/> to calculate area/volume, or common [syntactic](/source/syntax) rules and idioms of a particular [computer platform](/source/computer_platform), [application program](/source/application_program), or [formal language](/source/formal_language). It serves as an ad hoc [memory](/source/Memory_Almost_Full) aid for an experienced user.<ref name=":0">{{cite web|url=http://www.computerhistory.org/revolution/mainframe-computers/7/164/659|title=IBM System/360 and System/370 reference cards|quote=Technicians and operators carried cards with commonly needed information culled from the many reference manuals for each computer. A “green card” in your shirt pocket announced that you were an assembly-language programmer.}}</ref>

In spite of what the name ''reference card'' may suggest, such as a 3x5 [index card](/source/index_card) ({{convert|3|x|5|in|cm|0|disp=out}}), the term also applies to sheets of paper or online pages, as in the context of [programming language](/source/programming_language)s or [markup language](/source/markup_language)s. 
However, this concept is now being adopted to portray concise information in many other fields.

==Appearance==
As in the examples below, reference cards are typically one to a few pages in length. Pages are organized into one or more columns. Across the columns, the reference is split into sections and organized by topic. Each section contains a list of entries, with each entry containing a term and its description and usage information. Terms might include keywords, syntactic constructs, functions, methods, or macros in a computer language. In a reference card for a program with a graphical user interface, terms may include menu entries, icons or key combinations representing program actions.

Due to its logical structure and conciseness, finding information in a reference card is trivial for humans and requires no computer interaction. It is therefore convenient for a user to [print](/source/printing) out a reference card. While reference cards can be printed on [card stock](/source/card_stock), it is common to print them on ordinary printer paper. With the advent of portable electronic devices that can display documents, digital reference cards stored in [PDF](/source/PDF) or [HTML](/source/HTML) formats have become more common. This is in contrast to [user guide](/source/user_guide)s, which tend to be rather long and verbose and which have (in comparison to reference cards) a lower information density

==Examples==
* Wikimedia wiki syntax ref card [meta:Help:Reference card](/source/meta%3AHelp%3AReference_card)
* A [LaTeX](/source/LaTeX) reference sheet: [http://www.stdout.org/~winston/latex/latexsheet.pdf PDF]
* An AMS [LaTeX](/source/LaTeX) reference card: [http://www-control.eng.cam.ac.uk/~pcr20/latex/LaTeXRefCard.v1.0.pdf PDF]
* An [R](/source/R_(programming_language)) reference card: [https://cran.r-project.org/doc/contrib/Short-refcard.pdf PDF]
* An [R](/source/R_(programming_language)) reference card for [data mining](/source/data_mining): [http://www.rdatamining.com/docs/ www.rdatamining.com]
* A [CC (common criteria)](/source/CC_(common_criteria)) quick reference card for [security product evaluation](/source/security_product_evaluation): [http://www.school-of-technology.de/resources/ccQRC.pdf]

==See also==
* [Cheat sheet](/source/Cheat_sheet)
* [User guide](/source/User_guide)
* [Crib sheet](/source/Crib_sheet)

==References==
{{Reflist|refs=
<ref name="DC">
   "DC CAS Math Formula Reference Card | osse". Washington, D.C.,
   webpage:
   [http://osse.dc.gov/publication/dc-cas-math-formula-reference-card OSSE-refcard].
</ref>
}}

Category:Technical communication

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[pl:Ściąga#Inne rodzaje ściąg](/source/pl%3A%C5%9Aci%C4%85ga)

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Adapted from the Wikipedia article [Reference card](https://en.wikipedia.org/wiki/Reference_card) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Reference_card?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.