MivaScript Builtin Function, Miva Merchant 9+
miva_struct_members( aggregate var, members var )
<mvt:assign name="g.return_value" value="miva_struct_members( aggregate var, members var )" />
miva_struct_members( aggregate var, members var ) will populate an array "members" with the members of structure "aggregate". It returns the number of members in the structure.
aggregate var
members var