I work for an Orthotic & Prosthetic company so we get our fair share of pediatrics -- it's the largest O&P company in the nation so we get a lot of referrals because of contracted rates with insurance companies and because we are well known.
I really enjoy working with the lower extremities, but from a pediatric perspective we see all sorts of things: from scoliosis braces to pectus carinatum braces to cranial remolding orthoses, etc. -- I would rather be working with the F&A
Anyhow, that was off topic, to answer your question,
SMO (or SMAFO) is Supra Malleolar (Ankle) Foot Orthosis. As the name indicates, it goes up over the ankle -- it's late and I'm tired so I'll see if I can wiki something for you.
They are not limited to peds though, we make them for adults too.
I haven't shadowed a DPM yet, but do look forward to it, especially the surgical cases.