Correct, I do not know what the code is and can only go by what i'm reading since I do not use WL. However this is where I got my info from:
http://www2.wealth-lab.com/WL5Wiki/(S(xac032ybyilsn155tun1qwnb))/MACD.ashx?Code=1
towards the bottom I saw this line: "Wealth-Lab's classical MACD calculation is based on 2 EMAs with exponents 0.075 and 0.15. A 26 period EMA has an exponent of 0.074074 and the 12 has 0.153846. If you want to use approximate MACD instead of the classical indicator you can use [MACDEx], a custom indicator that lets you provide 2 periods for EMA."
Which lead me to believe that the classic MACD in WL uses the 26 and 12 EMAs and the MACDex indicator lets you chose the 2 EMA's used.
http://www2.wealth-lab.com/WL5Wiki/(S(xac032ybyilsn155tun1qwnb))/MACD.ashx?Code=1
towards the bottom I saw this line: "Wealth-Lab's classical MACD calculation is based on 2 EMAs with exponents 0.075 and 0.15. A 26 period EMA has an exponent of 0.074074 and the 12 has 0.153846. If you want to use approximate MACD instead of the classical indicator you can use [MACDEx], a custom indicator that lets you provide 2 periods for EMA."
Which lead me to believe that the classic MACD in WL uses the 26 and 12 EMAs and the MACDex indicator lets you chose the 2 EMA's used.