substr « String « Flash / Flex / ActionScript

1.	Working with Substring Values: substr
2.	Optionally omit the second parameter, substr returns a substring starting at the specified index and going to the end of the original string.
3.	Specifying a negative value simply counts backward from the end of the string where -1 is the last character.
4.	substring method returns a substring starting with the starting index specified and containing all the characters up to, but not including, the ending index.
5.	Use lastIndexOf to get the file name without extension name