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+# SNEWS2.0 and SCIMMA's hopskotch
+
+This page expands on the [quickstart](./quickstart.md) guide's discription of SCIMMA's hopskotch topics used by SNEWS2.0, as discussed in Section 1.2 of the [quickstart](./quickstart.md).
+
+## SNEWS2.0 SCIMMA groups
+
+A group is a collection of people with read and write access to the hop topics in it.  There are three groups associated with SNEWS:
+
+### The snews group
+
+The snews group is the one referred to in the [quickstart](./quickstart.md) guide.  It is used as a development area, so we can work with all the SNEWS software in a way which won't accidentally send out any alerts to the public topics, because all its topics are accessable only by members of the snews group.  It contains the following topics, with a description in parentheses:
+
+- snews.alert (Topic for alert coincidence: the snews output topic.)
+- snews.alert-firedrill (The alerts generated by a "firedrill" testing campaign.)
+- snews.alert-test (The alerts generated by test packets)
+- snews.experiments (Topic used by neutrino experiments to contribute potential SN alert data to snews.)
+- snews.experiments-firedrill (Topic used by neutrino experiments to contribute testl SN alert data to snews as part of a "firedrill" campaign.)
+- snews.experiments-test (Topic used by neutrino experiments to contribute test SN alert data to snews.)
+- snews.connection-testing (A topic used for the connection test feature of snews_pt: the confirmation of message sent comes back to the client on this topic.)
+- snews.operations (A topic used for different snews servers to coordinate operations.)
+
+### The snews2 group
+
+The snews2 group owns the public output topics for the production version of SNEWS2.0.  The credentials are owned by the operators of the servers, so the servers are the only thing with write access to the output topics. It contains the following topics, with a description in parentheses:
+
+- snews2.alert (Topic for alert coincidence: the snews output topic.)
+- snews2.alert-firedrill (The alerts generated by a "firedrill" testing campaign.)
+- snews2.alert-test (The alerts generated by test packets)
+- snews2.operations (A topic used for different snews servers to coordinate operations.)
+
+### The snews2-exp group
+
+The snews2-exp group owns the topics neutrino experiments use to send input to the SNEWS2.0 network.  Only the credentials used by each experiment's DAQ to send their information are in this group.
+
+- snews2-exp.experiments (Topic used by neutrino experiments to contribute potential SN alert data to snews.)
+- snews2-exp.experiments-firedrill (Topic used by neutrino experiments to contribute testl SN alert data to snews as part of a "firedrill" campaign.)
+- snews2-exp.experiments-test (Topic used by neutrino experiments to contribute test SN alert data to snews.)
+- snews2-exp.connection-testing (A topic used for the connection test feature of snews_pt: the confirmation of message sent comes back to the client on this topic.)
+