Are you talking about something like this?
https://docs.google.com/viewer?a=v&q=cache:wGqSko91zjgJ:www.portal.state.pa.us/portal/server.pt/document/432725/05100_sample_memorandum_of_understanding-mutual_aid_agreement_doc+&hl=en&gl=us&pid=bl&srcid=ADGEESjGR4JUom_B19ZJ0HQkVOn-4IaWPsBk1iq8L_7W1FbNB6Tb2kL4OZzrG96JlJQoLLxzsuUm2c_DMKZHAfuMbQXeVyI_dIXympbxQ25MN6LkVHnctbdFQvBMAd7IgHec2G-6mqBQ&sig=AHIEtbQgpeqJsbD1e-evdkOP5xqVzIdueQ&pli=1