Broadcast Audio Query

Hi,

Having strayed into the 'Audio Professionals' forum for the first time, I feel a little lost and out of place.

I have some audio to deliver for broadcast and have never had to deal with audio on such a level before. I have the direction of... 'The required set up level is zero level (PPM 4) @ 0 dBm with 18dB of digital headroom Programme sound peak levels should not exceed +8dB (PPM 6)' - Having Googled numerous parts of this, I could do with this translating for me.

I don't expect someone to break it all down for me as this has probably been asked hundreds of times before on here, but a link to a guide or rundown of what this means to an audio newbie would be greatly appreciated.

I'm running out various 4 x 22m mixes and have so far been bringing in to Audition, adjusting certain levels, bringing peaks down and applying a hard limiter to even out some parts. Now this has been brought to my attention (PPM / 18db Headroom) I thought I should stop in case I'm going down the completely wrong route.

Any help appreciated, thanks.