doc: Document that type-7 records must appear in ascending numerical order.

Every system file that I have seen puts them in this order, so I cannot
imagine that any other order receives any testing.

diff --git a/doc/dev/system-file-format.texi b/doc/dev/system-file-format.texi
index 3f82a4628e0918e1797e6c23a0670e42e0a5e8dc..b0b69dd4cae54f0922bd497232811ff1bd027c1f 100644 (file)
--- a/doc/dev/system-file-format.texi
+++ b/doc/dev/system-file-format.texi
@@ -60,7 +60,8 @@ if present.
 Document record, if present.
 
 @item
-Any records not explicitly included in this list, in any order.
+Extension (type 7) records, in ascending numerical order of their
+subtypes.
 
 @item
 Dictionary termination record.