Why not? It just happens to be the one number where the actual value is equivalent no matter the units (for all the units in the CSS spec anyway). Just because 0px == 0pt does not mean either form is wrong. Note also that Netscape (Mozilla) uses padding rather than margin. So to accomodate both you should have
as 0 can not be measured in units
margin-left: 0; padding-left: 0
I wasn't sure if this was still a problem, but this is because the numbers that are automatically inserted are placed within that extra marginal space, which we have just eliminated. You'll have to keep some margin there to allow room for the characters. 2em seems the smallest you can go before IE starts chopping off the numbers.
I tried what you suggested and it works but it doesnt list the numbers
margin-left: 2em; padding-left: 0