I would suggest the PHP docs on "split".
http://us3.php.net/split
Basically, split is used to create an array from a string that is seperated by a delimiter.
Here is an example:
Let's say you have a string:
Code:
blue,red,yellow,orange,green,purple
You can use the function to split this string into an array.
Code:
{assign var="color" value=","|split:"blue,red,yellow,orange,green,purple"}
Now, you can use this array.
Code:
{section name=mysec loop=$color}
{$color[mysec]}
{/section}
This should print out:
Code:
blue
red
yellow
orange
green
purple