I'm trying to build Freesurfer from developer sources and am running into this error:

mriio.c:3692:27: error: ‘STRING’ undeclared (first use in this function)
   status = output_volume((STRING)fname, nc_data_type, signed_flag, min, max,

Can you tell me where STRING comes from?  I could not find this datatype in either the sources or the dependencies.