--- a/toolkit/locales/en-US/chrome/global/extensions.properties
+++ b/toolkit/locales/en-US/chrome/global/extensions.properties
@@ -1,12 +1,20 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-csp.error.missing-directive = Policy is missing a required '%S' directive
+csp.error.missing-directive = Policy is missing a required "%S" directive
 
-csp.error.illegal-keyword = '%1$S' directive contains a forbidden %2$S keyword
+#LOCALIZATION NOTE (csp.error.illegal-keyword) %1$S is the name of a CSP directive, such as "script-src". %2$S is the name of a CSP keyword, usually 'unsafe-inline'.
+csp.error.illegal-keyword = "%1$S" directive contains a forbidden %2$S keyword
 
-csp.error.illegal-protocol = '%1$S' directive contains a forbidden %2$S: protocol source
+#LOCALIZATION NOTE (csp.error.illegal-protocol) %2$S a protocol name, such as "http", which appears as "http:", as it would in a URL.
+csp.error.illegal-protocol = "%1$S" directive contains a forbidden %2$S: protocol source
 
-csp.error.missing-host = %2$S: protocol requires a host in '%1$S' directives
+#LOCALIZATION NOTE (csp.error.missing-host) %2$S a protocol name, such as "http", which appears as "http:", as it would in a URL.
+csp.error.missing-host = %2$S: protocol requires a host in "%1$S" directives
 
-csp.error.missing-source = '%1$S' must include the source %2$S
+#LOCALIZATION NOTE (csp.error.missing-source) %1$S is the name of a CSP directive, such as "script-src". %2$S is the name of a CSP source, usually 'self'.
+csp.error.missing-source = "%1$S" must include the source %2$S
 
-csp.error.illegal-host-wildcard = %2$S: wildcard sources in '%1$S' directives must include at least one non-generic sub-domain (e.g., *.example.com rather than *.com)
+#LOCALIZATION NOTE (csp.error.illegal-host-wildcard) %2$S a protocol name, such as "http", which appears as "http:", as it would in a URL.
+csp.error.illegal-host-wildcard = %2$S: wildcard sources in "%1$S" directives must include at least one non-generic sub-domain (e.g., *.example.com rather than *.com)