Add naming guide and mention old name

Author: capnrefsmmat

docs/symptom-survey/index.md

@@ -65,12 +65,24 @@ the survey in publications based on the data. Specifically, we ask that you:
     A journal article describing the survey and its methods is currently in
     preparation, and we will update this page when it is available so that you
     can cite it instead.
-3. Send a copy of your publication, once it appears publicly as a preprint or
-   journal article, to <[email protected]>.
-
-Additionally, please note that the data use agreement requires that if you
-disclose survey microdata, Delphi must agree on the aggregation method that you
-will use to ensure reported estimates do not disclose any individual
-identifiable information, including individual survey results. If you are unsure
-whether a particular aggregation will prevent disclosure of individual survey
-results, please email us at <[email protected]>.
+3. The data use agreement requires that if you disclose survey microdata, Delphi
+   must agree on the aggregation method that you will use to ensure reported
+   estimates do not disclose any individual identifiable information, including
+   individual survey results. If you are unsure whether a particular aggregation
+   will prevent disclosure of individual survey results, please email us at
+   <[email protected]>.
+4. Finally, send a copy of your publication, once it appears publicly as a
+   preprint or journal article, to <[email protected]>.
+
+When referring to the survey in text, we prefer the following formats:
+
+* Long form (such as in an introduction or methods description): "The Delphi
+  Group at Carnegie Mellon University U.S. COVID-19 Trends and Impact Survey, in
+  partnership with Facebook".
+* Short form (used after the long form has been introduced): "The U.S. COVID-19
+  Trends and Impact Survey"
+* Acronym form: Delphi US CTIS
+
+Prior to July 2021, the survey was known as the COVID Symptom Survey (CSS), and
+some older documentation and publication may still refer to this name. We prefer
+that new publications and materials refer to the new name.