indenting code

Hi,

I'm asking myself if there is any common sense about
how to indent the code in smalltalk/squeak.

Most of the time I see something like

statement do: [ :parameter |
   otherStatement selector: [
        mostinnerstatement ] ].

or 

statement do: [ :parameter | otherStatement ].

Is this indenting common? Is the difference between those
two above depending on the length of the line? If it is,
how long are lines supposed to be? etc.

Any hints or links are appreciated.

thanks,

Norbert