diff --git a/Capabilities.md b/Capabilities.md
index 93049f7..f74d45b 100644
--- a/Capabilities.md
+++ b/Capabilities.md
@@ -1,6 +1,6 @@
 # Capabilities
 
-An overview from the mailing list archives - [Feb 2009 - Brian Warner](http://allmydata.org/pipermail/tahoe-dev/2009-February/001110.html):
+An overview from the mailing list archives - originally [Feb 2009 - Brian Warner](http://allmydata.org/pipermail/tahoe-dev/2009-February/001110.html):
 
 ```
  1: immutable file read-only capability string  URI:CHK:
@@ -26,6 +26,8 @@ derive #2 (but not the other way around). The full table is:
  #3->#4->#5
  #6->#7->#8
 
+Deriving a weaker capability from a strong one is called "diminishing" the stronger one.
+
 So we use "filecap" to talk about #1+#3+#4, but (since most files are
 immutable) we're usually talking about #1. We use "dircap" to talk about #6
 and #7. We use "readcap" to talk about #1,#4, and #7, but usually we refer to