aliases are normalized and used in normalized state, but nonnormalized aliases contain everything

common/proto/table_definition.proto

@@ -147,7 +147,12 @@ message GeneratedColumnAlias {
   // ignored, so a typo cannot pass silently.
   string generated_name = 1;
 
-  // What the column should be called instead. Same rules as any column name.
+  // What the column should be called instead. Preserved exactly for display.
+  // Aliases may contain Unicode letters, numbers, spaces, punctuation and
+  // symbols, but not leading/trailing whitespace or control characters, and
+  // are limited to 63 UTF-8 bytes. Uniqueness and lookup use a compatibility-
+  // normalized, Unicode-case-folded key that collapses whitespace and ignores
+  // emoji while keeping punctuation significant.
   string alias = 2;
 }