WBS numbering help, auto numbering with indenture

hi everyone.

here's what i want my end result to look like (think hundreds, thousands of line longer):

Column A:
1.4
1.4.1
1.4.1.1
1.4.1.2
1.4.1.3
1.4.2
1.4.2.1
1.4.2.2
1.4.2.3
1.4.2.3.1
1.4.2.4

Column B:
GROUND SYSTEM
Data Comm System Integrator
Program Management
System Engineering
Integration and Test
En Route Contractor
Program Management
System Engineering
Integration and Test
En Route Display System
Implementation


ETC

what i have is thousands of lines (indented to represent parent-child relationships for Column B....what i want is to automate Column A so that I don't have to phyiscally type in AND indent thousands of numbers.

I want to be able to type something into column B and for Column A to automatcially number it BASED on the indentation in column B AND it's order in the spreadsheet.

Also, note that the level (e.g. 1.1.1.1.1.1.1 a.ka. number of decimals ranges from 1 to 15)

can anyone help me please??

i would greatly appreciate it.

Thanks!!!