API Compound Data

hi, I writing an API node and need to get a data array to be accessible. I've looked through the docs, and I know that you add individual attributes like :

MFnNumericAttribute nAttr;
output = nAttr.create( "output", "out", FnNumericData::kFloat, 0.0 );

...

So how do you add an array? Nothing I try seems to work.

Ive had a look at the blindComplexDataCmd example, but I can't see how to get something like that on my own node.

Any help greatly appreciated

rob