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Definitions
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\newcommand: Define a new command. 
\newenvironment: Define a new environment. 
\newtheorem: Define a new theorem-like environment. 
\newfont: Define a new font name. 

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	\newcommand ::newcommand::renewcommand::
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 \newcommand{cmd}[args]{definition}
 \newcommand{cmd}[args][default]{definition}
 \renewcommand{cmd}[args]{definition}
 \renewcommand{cmd}[args][default]{definition}
These commands define (or redefine) a command. 
	cmd	A command name beginning with a \. For 
		\newcommand it must not be already defined and 
		must not begin with \end; for \renewcommand it 
		must already be defined. 
	args	An integer from 1 to 9 denoting the number of 
		arguments of the command being defined. The 
		default is for the command to have no arguments. 
	def	If this optional parameter is present, it means 
		that the command's first argument is optional. 
		The default value of the optional argument is def. 
	definition	The text to be substituted for every 
		occurrence of cmd; a parameter of the form #n in 
		cmd is replaced by the text of the nth argument 
		when this substitution takes place. 
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	\newenvironment ::newenvironment::renewenvironment::
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 \newenvironment{nam}[args]{begdef}{enddef}
 \newenvironment{nam}[args][default]{begdef}{enddef}
 \renewenvironment{nam}[args]{begdef}{enddef}
These commands define or redefine an environment. 
	nam	The name of the environment. For \newenvironment 
		there must be no currently defined environment 
		by that name, and the command \nam must be 
		undefined. For \renewenvironment the environment 
		must already be defined. 
	args	An integer from 1 to 9 denoting the number of 
		arguments of the newly-defined environment. 
		The default is no arguments. 
	default	If this is specified, the first argument 
		is optional, and default gives the default value 
		for that argument. 
	begdef	The text substituted for every occurrence of 
		\begin{nam}; a parameter of the form #n in cmd 
		is replaced by the text of the nth argument when 
		this substitution takes place. 
	enddef	The text substituted for every occurrence of 
		\end{nam}. It may not contain any argument 
		parameters. 
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	\newtheorem ::newtheorem::
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 \newtheorem{env_name}{caption}[within]
 \newtheorem{env_name}[numbered_like]{caption}
This command defines a theorem-like environment. 
	env_name	The name of the environment to be defined. 
			A string of letters. It must not be the 
			name of an existing environment or counter. 
	caption	The text printed at the beginning of the 
			environment, right before the number. 
			This may simply say "Theorem", for example. 
	within		The name of an already defined counter, 
			usually of a sectional unit. Provides a 
			means of resetting the new theorem counter 
			within the sectional unit. 
	numbered_like	The name of an already defined theorem-like 
			environment. 
The \newtheorem command may have at most one optional argument. 
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	\newfont ::newfont::
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\newfont{cmd}{font_name} 
Defines the command name cmd, which must not be currently 
defined, to be a declaration that selects the font named 
font_name to be the current font.