Forum:Are holograms physically solid??

Does anyone know the general rule regarding holographic technology? Cos in on the site there is a hologym, which would presumably use solid obstacles (otherwise its use is greatly reduced - think like a holodeck or the EMH for all you Star Trek fans); yet simultaneously, in Exile, Admiral Limpan calls for a sitrep of Commenorian and Bothan forces breaking the Corellian blockade, it says that she is standing in the middle of the hologram.

Can anyone provide answers??