Created SC2297 (markdown)

SC2297.md

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+## Double quotes must be outside ${}: ${"invalid"} vs "${valid}".
+
+### Problematic code:
+
+```sh
+echo ${"USER"}
+```
+
+### Correct code:
+
+```sh
+echo "${USER}"
+```
+
+### Rationale:
+
+ShellCheck found a parameter expansion containing what appears to be a quoted variable name.
+
+While the parameter expansion itself must be quoted, as in `"${valid}"`, the quotes may not appear inside the `{}` as in `${"invalid"}`.
+
+Also note that translated strings like `$"Hello"` may not use curly braces.
+
+### Exceptions:
+
+None
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!