diff --git a/doc/manual.adoc b/doc/manual.adoc
index 6224658..6780bb5 100644
--- a/doc/manual.adoc
+++ b/doc/manual.adoc
@@ -42,3 +42,14 @@ accidentally corrupt each other.
 
 Schema File
 ~~~~~~~~~~~
+
+The schema file is a CSV (colon-separated values) file.  The first entry in the
+file consist of the values `fmt`, the format version number, and `newfol schema
+file`.
+
+newfol automatically upgrades schema files to the latest version, which at the
+time of this writing, was 3.  If no schema file exists, newfol will
+automatically create a version 0 schema file and upgrade it to the latest
+version on start.  newfol does not accept schema files that have a newer version
+than it currently supports, but it ignores directives it does not understand,
+and so can be manually downgraded by editing the `fmt` directive.