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# '''Square Brackets Rule''': Enclose arguments to ConTeXt commands in [ ].
Continuing to sandbox an intro to ConTeXt.
Two rules of syntax:
# '''Square Brackets Rule''': Enclose arguments to ConTeXt commands in [ ].
# '''Curly Braces Rule''': To group some text as a single self-contained unit, enclose the text in { }.
Three principles of organization:
# '''Creating Principle''': To create a named customization of ''something'', use {{code|\define''something''}}.
== A minimal example : the Applying and Configuring Principles ==
To see how these rules and principles work, let’s start with a minimal example of a ConTeXt document:
<texcode>
</texcode>
The Configuring Principle is being applied here again. The way that paragraphs are indented in a ConTeXt is called {{code|indenting}}, so you use {{cmd|setupindenting}} to configure it. The use of [ ] to enclose the arguments is again in keeping with the Square Brackets Rule.
== Another example: The Creating Principle ==
Let’s look at another example. Suppose you have a ConTeXt document, and you want to place a box with rounded corners around some text. The way to place boxes around text in ConTeXt is called {{code|framed}}, so (in keeping with the Applying Principle) to apply that type of formatting you enclose the text in {{cmd|startframed}} {{cmd|stopframed}}. Since you want rounded corners, you specify the argument {{code|1=corner=round}} for rounded corners too:
<context source="yes">
\startframed[corner=round]
An example of something.
\stopframed
</context>
As you can see, you put the arguments in according to the Square Brackets Rule. But what if you want to make this configuration the default for ''all'' of your frames in the document? You can use the Configuring Principle for this. The command {{cmd|setupframed|[corner=round]}} will make this the default configuration for the rest of the document:
<context source="yes">
\setupframed[corner=round]
\startframed
An example of something.
\stopframed
</context>
When you have set it up this way, you no longer have to type in the arguments every time you have a box around text. But more importantly, by making this configuration separately at the beginning of your document, you have set up a uniform style throughout your document. This makes it easy to make global style adjustments, which is a very powerful feature.
But what if you want to have two types of frames, one with rounded corners and one without, and you'll be using both of them lots of times? This is where the Creating Principle comes in. You can use {{cmd|defineframed}} twice to define two meaningfully named configurations (say {{code|definitionFrame}} with rectangular corners and {{code|exampleFrame}} with rounded corners) that you can refer to throughout your document:
<context source="yes">
\defineframed[definitionFrame][align=flushleft]
\defineframed[exampleFrame][align=flushleft, corner=round]
\startframed[definitionFrame]
A definition of something.
\stopframed
\startframed[exampleFrame]
An example of something.
\stopframed
</context>
Now if at some later time you want to change the way that you format the frames around your definitions and examples, it is easy to do so. You just change the {{cmd|defineframed}} commands where they are set up, and the change will be applied consistently and globally to your whole document.
== Example: the Curly Braces Rule ==
You have seen examples of how the three basic Principles can be applied in ConTeXt, and of how the Square Brackets Rule can be applied, but we haven’t yet looked at the Curly Braces Rule.
To see one way that the Curly Braces Rule is used, note that enclosing text in {{cmd|startframed}} {{cmd|stopframed}} is not the only way to put a box around text. Another way, which is really just syntactic sugar for the same thing, is to used the {{cmd|framed}} command. This will put a box around the next single unit following it (ignoring whitespace). For example:
<context source="yes">
\framed {An example of something}
</context>
== Summary ==
Naturally not everything in ConTeXt can be derived from these two basic Rules and three basic Principles. There are many further details to learn in order to implement them, and not everything in ConTeXt is completely consistent with these Rules and Principles. However, they serve as a useful guide, and the design of ConTeXt really is remarkably consistent with these Rules and Principles, so they serve as a useful guide when you are trying to figure out how best to use the powerful tools that ConTeXt offers.
