tuned output;

--- a/src/Pure/Thy/bibtex.scala	Tue Dec 27 17:35:01 2022 +0100
+++ b/src/Pure/Thy/bibtex.scala	Tue Dec 27 22:08:31 2022 +0100
@@ -201,6 +201,8 @@
   }
 
   final class Entries private(val entries: List[Text.Info[String]], val errors: List[String]) {
+    override def toString: String = "Bibtex.Entries(" + entries.length + ")"
+
     def ::: (other: Entries): Entries =
       new Entries(entries ::: other.entries, errors ::: other.errors)
   }

--- a/src/Pure/Thy/file_format.scala	Tue Dec 27 17:35:01 2022 +0100
+++ b/src/Pure/Thy/file_format.scala	Tue Dec 27 22:08:31 2022 +0100
@@ -8,7 +8,9 @@
 
 
 object File_Format {
-  object No_Data extends AnyRef
+  object No_Data extends AnyRef {
+    override def toString: String = "File_Format.No_Data"
+  }
 
   sealed case class Theory_Context(name: Document.Node.Name, content: String)