--- a/doc/Simtool-command-shell	Sun Mar 21 06:24:52 2021 +0000
+++ b/doc/Simtool-command-shell	Sun Mar 21 06:42:29 2021 +0000
@@ -1,10 +1,12 @@
 Our fc-simtool and fc-uicc-tool operate as interactive shells.  When you run
-either program, it selects the "card reader" device it will use and connects to
-the card via pcsc-lite facilities, and then it gives you an interactive command
-shell.  The communication session with the card (including vital volatile state
-like PIN authentication and currently selected directory and EF) remains
-unbroken until you exit the shell, at which point our tools tell pcsc-lite to
-power down the card.
+either program, it selects (based on -d or -p options) the card access back end
+it will use, and if the card connection is successful (ATR will be displayed),
+the program gives you an interactive command shell.  The communication session
+with the card (including vital volatile state like PIN authentication and
+currently selected directory and EF) remains unbroken until you exit the shell,
+at which point our tools clean up: in the case of PC/SC readers, we tell
+pcsc-lite to power down the card; if you are using the Calypso back end
+(fc-simint), the Calypso device will be commanded into soft power-off.
 
 The actual useful commands available in fc-simtool and fc-uicc-tool are
 described in other documents; this document describes program invokation and
@@ -15,23 +17,21 @@
 
 Both tools share the same command line structure:
 
-fc-simtool [-p num] [batch-command]
-fc-uicc-tool [-p num] [batch-command]
+fc-simtool {-d /dev/ttyXXX | -p N} [batch-command]
+fc-uicc-tool {-d /dev/ttyXXX | -p N} [batch-command]
+
+The target selection option (-d or -p, see Back-end-selection article) is
+mandatory - there is no default.  If you run fc-simtool or fc-uicc-tool with
+just the required -d or -p target selection option and no other arguments, the
+program will enter the interactive command shell.
 
-If you run either tool without any options or arguments, it will select the
-first reader supported by pcsc-lite (reader number 0, same as if -p0 was
-specified), and if the card connection is successful, it will enter the
-interactive command shell.  Use the -p num option to select a different reader
-number; to tell which reader number is which, use fc-pcsc-list to list all
-available readers.
+Aside from target selection and other back end options, any arguments given on
+the command line suppress the default interactive shell and select the tool's
+batch mode instead - the arguments specify the command to be executed.  For
+example, the following invokation will read and display the inserted card's
+ICCID, and immediately exit:
 
-Aside from the -p num option, any arguments given on the command line suppress
-the default interactive shell and select the tool's batch mode instead - the
-arguments specify the command to be executed.  For example, the following
-invokation will read and display the inserted card's ICCID, and immediately
-exit:
-
-fc-simtool iccid
+fc-simtool -p0 iccid
 
 This batch mode is particularly useful with the exec command described further
 in this document.