METAR Remarks

[Xacto]

Try this one. http://205.156.54.206/oso/oso1/oso12...2.htm#ch12link
Scroll down to para 12.7
Here is a link to FAA Order 7340 referred to in the text.
http://www.faa.gov/atpubs/CNT/CNTHME.htm
Still can't figure what AC4 means though, perhaps Bithday Boy's suggestion isn't too far from the truth!

Xacto.