diff --git a/doc/apps.texi b/doc/apps.texi
index 6fc90937c..61cedf56d 100644
--- a/doc/apps.texi
+++ b/doc/apps.texi
@@ -190,6 +190,16 @@ and the cells specified in $HOME/.TheseCells.
 More usefully it will look at and ~/.TheseCells in your home directory
 and for each line which is a cell get afs token for these cells.
 
+The TheseCells file defines the the cells to which applications on the
+local client machine should try to aquire tokens for. It must reside in
+the directories searched by @manpage{kafs,3} on every AFS client machine.
+
+The file is in ASCII format and contains one character string, the cell
+name, per line. Cell names are case sensitive, but most cell names
+are lower case.
+
+See manpage for manpage{kafs,3} for search locations of ThisCell and TheseCells.
+
 @subsection How to get a KeyFile
 
 @file{ktutil -k AFSKEYFILE:KeyFile get afs@@MY.REALM}