@@ -559,9 +559,9 @@ private static void VerifyCollectionName(string collectionName)
 
         foreach (char character in collectionName)
         {
-            if (!((character is >= 'a' and <= 'z') || (character is >= 'A' and <= 'Z') || (character is >= '0' and <= '9')))
+            if (!((character is >= 'a' and <= 'z') || (character is >= 'A' and <= 'Z') || (character is >= '0' and <= '9') || character is '_'))
             {
-                throw new ArgumentException("Collection name must contain only ASCII letters and digits.", nameof(collectionName));
+                throw new ArgumentException("Collection name must contain only ASCII letters and digits or underscores. The first character must be an upper case letter.", nameof(collectionName));
             }
         }
     }
Original file line number	Diff line number	Diff line change
`@@ -559,9 +559,9 @@ private static void VerifyCollectionName(string collectionName)`
`559`	`559`
`560`	`560`	`foreach (char character in collectionName)`
`561`	`561`	`{`
`562`		`- if (!((character is >= 'a' and <= 'z') \|\| (character is >= 'A' and <= 'Z') \|\| (character is >= '0' and <= '9')))`
	`562`	`+ if (!((character is >= 'a' and <= 'z') \|\| (character is >= 'A' and <= 'Z') \|\| (character is >= '0' and <= '9') \|\| character is '_'))`
`563`	`563`	`{`
`564`		`- throw new ArgumentException("Collection name must contain only ASCII letters and digits.", nameof(collectionName));`
	`564`	`+ throw new ArgumentException("Collection name must contain only ASCII letters and digits or underscores. The first character must be an upper case letter.", nameof(collectionName));`
`565`	`565`	`}`
`566`	`566`	`}`
`567`	`567`	`}`