diff --git a/debian/changelog b/debian/changelog
index fa8bb0f938..9fd96de95b 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,8 +1,8 @@
 git-annex (0.04) UNRELEASED; urgency=low
 
-  * Add checkout subcommand, which allows checking out file content
-    in preparation of changing it.
-  * Add uncheckout subcommand.
+  * Add unlock subcommand, which replaces the symlink with a copy of
+    the file's content in preparation of changing it.
+  * Add lock subcommand.
   * Add build dep on libghc6-testpack-dev.
   * Add annex.version, which will be used to automate upgrades
     between incompatable versions.
diff --git a/doc/git-annex.mdwn b/doc/git-annex.mdwn
index 3bb3b08357..61f0f8fca6 100644
--- a/doc/git-annex.mdwn
+++ b/doc/git-annex.mdwn
@@ -81,9 +81,10 @@ Many git-annex subcommands will stage changes for later `git commit` by you.
   git-annex may refuse to drop content if the backend does not think
   it is safe to do so, typically because of the setting of annex.numcopies.
 
-* checkout [path ...]
+* unlock [path ...]
 
-  Checks out annexed files so they can be modified. This replaces the
+  Normally, the content of annexed files is protected from being changed.
+  Unlocking a annexed file allows it to be modified. This replaces the
   symlink for each specified file with a copy of the file content.
   When you `git commit`, the file, the new content is injected back into
   the annex.
@@ -102,10 +103,10 @@ Many git-annex subcommands will stage changes for later `git commit` by you.
   and sets up `.gitattributes` and the pre-commit hook.
   This is an optional, but recommended step.
 
-* uncheckout [path ...]
+* lock [path ...]
 
-  Use this to undo a checkout command if you don't want to modify
-  the checked out files, or have made modifications you want to discard.
+  Use this to undo an unlock command if you don't want to modify
+  the files, or have made modifications you want to discard.
 
 * unannex [path ...]
 
diff --git a/doc/todo/backendSHA1.mdwn b/doc/todo/backendSHA1.mdwn
index 44df406dea..8c16b75ad0 100644
--- a/doc/todo/backendSHA1.mdwn
+++ b/doc/todo/backendSHA1.mdwn
@@ -4,4 +4,4 @@ In particular, while files can be added using it, git-annex will not notice
 when their content changes, and will not create a new key for the new sha1
 of the net content.
 
-[[done]]; use checkout subcommand
+[[done]]; use unlock subcommand and commit changes with git
diff --git a/doc/walkthrough.mdwn b/doc/walkthrough.mdwn
index cb564fa979..29922bd75e 100644
--- a/doc/walkthrough.mdwn
+++ b/doc/walkthrough.mdwn
@@ -192,23 +192,23 @@ makes it very easy.
 
 ## modifying annexed files
 
-Normally, the content of files in the annex cannot be modified.
-In order to modify a file, it should first be checked out:
+Normally, the content of files in the annex is prevented from being modified.
+In order to modify a file, it should first be unlocked:
 
-	# git annex checkout my_cool_big_file
-	checkout my_cool_big_file (copying...) ok
+	# git annex unlock my_cool_big_file
+	unlock my_cool_big_file (copying...) ok
 
-Checking a file out replaces the symlink that normally points at its content
-with a copy of the content. You can then modify the file like any regular
-file. Because it is a regular file.
+They replaces the symlink that normally points at its content with a copy
+of the content. You can then modify the file like any regular file. Because
+it is a regular file.
 
 When you `git commit`, git-annex's pre-commit hook will automatically
-notice that you are committing a checked-out file, and add its new content
+notice that you are committing an unlocked file, and add its new content
 to the annex. The file will be replaced with a symlink to the new content,
 and this symlink is what gets committed to git.
 
 If you decide you don't need to modify the file after all, or want to discard
-modifications, just use the uncheckout subcommand to undo the checkout.
+modifications, just use the lock subcommand.
 
 ## using the URL backend