OZ: I am about to apply to the ACS for assessment and there is some info about applying for a specific MODL. If I dont put one in will they decide which one I am?....
What happens if my job meets two different MODL codes? What if you put a MODL code down and they dont agree with the code...will they just throw it out or will they put a code down that they feel more accurately reflects your skills and experience?

Sorry the sudden flurry of questions, I want to make sure the ACS stuff is spot on before I send it.

Thanks again.

If you don't put an MODL code in then your application will be invalid. You need to list the code that best describes your skills/position, if ACS think a different code describes your skills/position they'll let you know.