no it is not restricted to Somerville, but will probably draw most from Somerville.

Medford is taking it seriously: http://www.wickedlocal.com/medford/topstories/x1626870826/Medford-School-Committee-opposes-new-Somerville-charter-school#axzz1funQHBl2

Jamilla Xible (sp?) a leading founder of the charter school group used to live in Somerville, but moved to Lexington. I guess she left the old address on the document which is a bit misleading, but an understandable mistake.