\newenvironment

LaTeX2e help 1.6

### 2.3.2: \newenvironment

       \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.